Inconsistent behaviour in resample between daily and weekly
Resampling weekly doesn't behave the same way as resampling daily when using label='right'.

``` python

import numpy as np
import pandas as pd

dates = pd.date_range('2001-01-01 10:00', '2001-01-15 16:00', freq='12h')
d = pd.DataFrame(dict(A=np.arange(len(dates))), index=dates)
```

so d looks like this:

```
                      A
2001-01-01 10:00:00   0
2001-01-01 22:00:00   1
2001-01-02 10:00:00   2
2001-01-02 22:00:00   3
2001-01-03 10:00:00   4
2001-01-03 22:00:00   5
2001-01-04 10:00:00   6
2001-01-04 22:00:00   7
2001-01-05 10:00:00   8
2001-01-05 22:00:00   9
2001-01-06 10:00:00  10
2001-01-06 22:00:00  11
<truncated>
```

Then we resample daily:

``` python
d.resample('D', label='right').last()
```

Produces the following output. 

```
             A
2001-01-02   1
2001-01-03   3
2001-01-04   5
2001-01-05   7
2001-01-06   9
<truncated>
```

Note that the value for 2001-01-05 is 7, the last value on 2001-01-04 in the original dataframe.  If we resample weekly:

``` python
d.resample('W-FRI', label='right').last()
```

Output is 

```
             A
2001-01-05   9
2001-01-12  23
2001-01-19  29
```

This time, the value labelled 2001-01-05 is the last value on 2001-01-05 _not_ the last value on 2001-01-04. This is inconsistent with the behaviour for daily resample, where the label is always strictly after the data. 

The result I expect is 

```
             A
2001-01-06   9
2001-01-13  23
2001-01-20  29
```

as the end of a W-FRI bucket should be midnight on the following Saturday. This is consistent with the daily resampling behaviour where the end of the 2001-01-05 bucket is midnight on 2001-01-06. 

Output of installed versions below. 

```
INSTALLED VERSIONS
------------------
Python: 2.7.3.final.0
OS: Linux
Release: 2.6.18-308.el5
Processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_GB

pandas: 0.13.0
Cython: Not installed
Numpy: 1.7.1
Scipy: 0.9.0
statsmodels: Not installed
    patsy: Not installed
scikits.timeseries: Not installed
dateutil: 1.5
pytz: 2011k
bottleneck: Not installed
PyTables: 2.3.1-1
    numexpr: 2.0.1
matplotlib: 1.1.1
openpyxl: Not installed
xlrd: 0.8.0
xlwt: 0.7.4
xlsxwriter: Not installed
sqlalchemy: 0.8.2
lxml: 2.3.6
bs4: Not installed
html5lib: 0.90
bigquery: Not installed
apiclient: Not installed
```
