Cannot resample with 'D' and tz aware timeseries
``` python
from pandas import *
dr = date_range(start='2012-5-1', end='2012-6-1')
ts = Series(range(len(dr)), dr)
ts_utc = ts.tz_localize('UTC')
ts_local = ts_utc.tz_convert('America/Los_Angeles')
ts_local.resample('D')
```

yields..

``` traceback
/env/lib/python2.7/site-packages/pandas/tseries/resample.pyc in _get_time_bins(self, axis)
     97         # a little hack
     98         trimmed = False
---> 99         if len(binner) > 2 and binner[-2] == axis[-1] and self.closed == 'right':
    100             binner = binner[:-1]
    101             trimmed = True

/env/lib/python2.7/site-packages/pandas/lib.so in pandas.lib._Timestamp.__richcmp__ (pandas/src/tseries.c:33751)()

Exception: Cannot compare tz-naive and tz-aware timestamps
```
