Module xlrd is not installed with 0.14; creates an Import Error when using read_excel
After doing

```
conda create -n dummy_python python=2.7 pandas=0.14 ipython=2.0
```

and then activating dummy_python, I get the following error with a simple .xlsx file that has 3 sheets:

``` python
In [4]: pandas.read_excel('candidate_test.xlsx', sheetname='prices')
---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
<ipython-input-4-ad7ce8e2fc77> in <module>()
----> 1 pandas.read_excel('candidate_test.xlsx', sheetname='prices')

/home/ely/anaconda/envs/dummy_python/lib/python2.7/site-packages/pandas/io/excel.pyc in read_excel(io, sheetname, **kwds)
    111     engine = kwds.pop('engine', None)
    112 
--> 113     return ExcelFile(io, engine=engine).parse(sheetname=sheetname, **kwds)
    114 
    115 

/home/ely/anaconda/envs/dummy_python/lib/python2.7/site-packages/pandas/io/excel.pyc in __init__(self, io, **kwds)
    129     def __init__(self, io, **kwds):
    130 
--> 131         import xlrd  # throw an ImportError if we need to
    132 
    133         ver = tuple(map(int, xlrd.__VERSION__.split(".")[:2]))

ImportError: No module named xlrd
```

But with pandas 0.13.1, the same sheet parses with no error from the same command:

``` python
In [2]: pandas.version.version
Out[2]: '0.13.0'

In [3]: pandas.read_excel('candidate_test.xlsx', sheetname='prices')
Out[3]: 
          date      time         millis      bid    offer
0   2012.09.30  22:00:15  1349042415003  1.28490  1.28495
1   2012.09.30  22:00:16  1349042416203  1.28485  1.28495
2   2012.09.30  22:00:18  1349042418302  1.28480  1.28495
3   2012.09.30  22:03:37  1349042617304  1.28480  1.28500
4   2012.09.30  22:05:17  1349042717103  1.28485  1.28500
5   2012.09.30  22:06:05  1349042765403  1.28490  1.28500
6   2012.09.30  22:06:06  1349042766404  1.28495  1.28500
7   2012.09.30  22:06:53  1349042812903  1.28495  1.28505
8   2012.09.30  22:06:53  1349042813004  1.28495  1.28500
9   2012.09.30  22:07:59  1349042879103  1.28485  1.28500
10  2012.09.30  22:08:03  1349042882703  1.28490  1.28500
11  2012.09.30  22:08:04  1349042883903  1.28495  1.28500
12  2012.09.30  22:08:05  1349042885304  1.28485  1.28490
13  2012.09.30  22:08:07  1349042886503  1.28480  1.28490
14  2012.09.30  22:08:13  1349042892702  1.28480  1.28485
15  2012.09.30  22:08:20  1349042900103  1.28475  1.28485
16  2012.09.30  22:08:20  1349042900204  1.28475  1.28480
17  2012.09.30  22:08:38  1349042917604  1.28425  1.28470
18  2012.09.30  22:08:38  1349042917702  1.28460  1.28470
19  2012.09.30  22:08:38  1349042918005  1.28460  1.28480
20  2012.09.30  22:08:39  1349042919103  1.28425  1.28480
21  2012.09.30  22:08:39  1349042919202  1.28450  1.28480
22  2012.09.30  22:08:40  1349042919503  1.28440  1.28480
23  2012.09.30  22:08:49  1349042928702  1.28440  1.28485
24  2012.09.30  22:08:49  1349042929003  1.28440  1.28480
25  2012.09.30  22:10:12  1349043011803  1.28440  1.28475
26  2012.09.30  22:10:12  1349043012004  1.28440  1.28480
27  2012.09.30  22:10:17  1349043017204  1.28440  1.28465
28  2012.09.30  22:11:37  1349043096604  1.28440  1.28450
29  2012.09.30  22:11:40  1349043099503  1.28430  1.28440
30  2012.09.30  22:11:40  1349043099604  1.28430  1.28465
31  2012.09.30  22:11:46  1349043105703  1.28430  1.28440
32  2012.09.30  22:11:46  1349043106105  1.28430  1.28465
33  2012.09.30  22:12:58  1349043178004  1.28430  1.28460
34  2012.09.30  22:13:13  1349043192503  1.28430  1.28465
35  2012.09.30  22:13:40  1349043220003  1.28425  1.28465
36  2012.09.30  22:13:43  1349043222903  1.28430  1.28465
37  2012.09.30  22:15:32  1349043331903  1.28460  1.28465
38  2012.09.30  22:15:34  1349043334303  1.28440  1.28465
39  2012.09.30  22:15:35  1349043334503  1.28430  1.28465
40  2012.09.30  22:15:35  1349043334603  1.28460  1.28465
41  2012.09.30  22:15:36  1349043335902  1.28425  1.28465
42  2012.09.30  22:15:36  1349043336004  1.28440  1.28465
43  2012.09.30  22:15:38  1349043337703  1.28440  1.28460
44  2012.09.30  22:15:38  1349043337803  1.28425  1.28460
45  2012.09.30  22:15:38  1349043337902  1.28430  1.28460
46  2012.09.30  22:15:40  1349043339603  1.28430  1.28465
47  2012.09.30  22:15:55  1349043354903  1.28470  1.28485
48  2012.09.30  22:15:57  1349043356702  1.28450  1.28485
49  2012.09.30  22:16:57  1349043417003  1.28450  1.28480
50  2012.09.30  22:17:09  1349043429302  1.28450  1.28475
51  2012.09.30  22:17:17  1349043436702  1.28425  1.28475
52  2012.09.30  22:17:17  1349043436802  1.28440  1.28475
53  2012.09.30  22:17:23  1349043442802  1.28470  1.28475
54  2012.09.30  22:17:24  1349043443702  1.28425  1.28475
55  2012.09.30  22:17:24  1349043443803  1.28450  1.28475
56  2012.09.30  22:17:48  1349043468303  1.28425  1.28475
57  2012.09.30  22:17:48  1349043468404  1.28440  1.28475
58  2012.09.30  22:17:57  1349043476904  1.28450  1.28475
59  2012.09.30  22:18:10  1349043490303  1.28450  1.28465
           ...       ...            ...      ...      ...

[34650 rows x 5 columns]
```

So the question is, why was a dependency on XLRD introduced, but the library is not installed as a dependency when pandas is installed through conda?
