Reading of fixed width file is detecting incorrect number of columns
Hi,
I have been trying to use the `read_fwf()` dataframe method in pandas 0.16.0. I have supplied a list of tuples for the _colspec_ parameter. There are 9 tuples specified. I have also supplied a list to the _names_ parameter, with 9 column names. 

Here's some code:

```
df = pd.read_fwf('c:/6starts.tab', 
    header=None,
    colspec=[(0, 11), (11, 14), (14, 43), (43, 49), (49, 69), (69, 98), (98, 110), (110, 133), (133, 145)], 
    names=['lotid', 'lottype', 'part', 'qty', 'startdate', 'proc', 'rnum', 'material', 'who'])
```

Here's the traceback (sorry about the formatting):

---

ValueError                                Traceback (most recent call last)
<ipython-input-15-ff4a00f4ef2b> in <module>()
     10                                      (110, 133),
     11                                      (133, 145)], 
---> 12                             names=['lotid', 'lottype', 'part', 'qty', 'startdate', 'proc', 'rnum', 'material', 'who']
     13                             )

C:\Program Files\Anaconda\lib\site-packages\pandas\io\parsers.py in read_fwf(filepath_or_buffer, colspecs, widths, **kwds)
    499     kwds['colspecs'] = colspecs
    500     kwds['engine'] = 'python-fwf'
--> 501     return _read(filepath_or_buffer, kwds)
    502 
    503 

C:\Program Files\Anaconda\lib\site-packages\pandas\io\parsers.py in _read(filepath_or_buffer, kwds)
    254         return parser
    255 
--> 256     return parser.read()
    257 
    258 _parser_defaults = {

C:\Program Files\Anaconda\lib\site-packages\pandas\io\parsers.py in read(self, nrows)
    713                 raise ValueError('skip_footer not supported for iteration')
    714 
--> 715         ret = self._engine.read(nrows)
    716 
    717         if self.options.get('as_recarray'):

C:\Program Files\Anaconda\lib\site-packages\pandas\io\parsers.py in read(self, rows)
   1561             content = content[1:]
   1562 
-> 1563         alldata = self._rows_to_cols(content)
   1564         data = self._exclude_implicit_index(alldata)
   1565 

C:\Program Files\Anaconda\lib\site-packages\pandas\io\parsers.py in _rows_to_cols(self, content)
   1936             msg = ('Expected %d fields in line %d, saw %d' %
   1937                    (col_len, row_num + 1, zip_len))
-> 1938             raise ValueError(msg)
   1939 
   1940         if self.usecols:

**ValueError: Expected 9 fields in line 1, saw 7**

---

The problem I'm seeing is that pandas does not appear to be using _colspec_ to parse the file. Instead it seems to be using whitespace and is detecting 7 distinct columns based on that.

I have tried specifying `delimiter=''`to see if that would make a difference, but it doesn't fix it. I have also tried specifying `usecols=[0, 1, 2, 3, 4, 5, 6, 7, 8]` and that seems to prevent the exception occurring, but it still only reads in 7 columns and pads the last 2 columns with _NaN_.

![pandas_1](https://cloud.githubusercontent.com/assets/8472772/7771371/c0dc4b56-008e-11e5-934e-96dbeffdea63.jpg)

In the snapshot above, the first column is fine, however the 2nd and 3rd columns are merged together (the 'D ' and the '8SL*****' bit). The next snapshot shows some of the desired column widths (highlighted in pink):

![pandas_4](https://cloud.githubusercontent.com/assets/8472772/7771735/74ec4018-0091-11e5-84c6-54a29e2ebd88.jpg)

I think the issue is in the PythonParser class within the parsers.py file, in the __rows_to_cols()_ method, but I'm not familiar enough with it yet to attempt any sort of fix.

Here is the version information from pandas.show_versions():
## INSTALLED VERSIONS

commit: None
python: 2.7.6.final.0
python-bits: 64
OS: Windows
OS-release: 7
machine: AMD64
processor: Intel64 Family 6 Model 58 Stepping 9, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None

pandas: 0.16.0
nose: 1.3.4
Cython: 0.22
numpy: 1.9.2
scipy: 0.15.1
statsmodels: 0.6.1
IPython: 3.1.0
sphinx: 1.2.3
patsy: 0.3.0
dateutil: 2.4.1
pytz: 2015.2
bottleneck: None
tables: 3.1.1
numexpr: 2.3.1
matplotlib: 1.4.3
openpyxl: 1.8.5
xlrd: 0.9.3
xlwt: 0.7.5
xlsxwriter: 0.6.7
lxml: 3.4.2
bs4: 4.3.2
html5lib: None
httplib2: None
apiclient: None
sqlalchemy: 0.9.9
pymysql: None
psycopg2: None

Please let me know if you need any more information.

Thanks,
Adrian.
