Timezone-aware times are inconsistent using object or datetime64
I just upgraded to 0.14 and am seeing an inconsistent behavior when converting datetimes to objects.  This used to be consistent in 0.12.1 and now it loses timezone information when converting to datetime64.  Is this expected?

```
import pytz
import datetime
from pandas import DataFrame
tz = pytz.timezone('US/Eastern')
dt = tz.localize(datetime.datetime(2012, 6, 1))
dt
Out[31]: datetime.datetime(2012, 6, 1, 0, 0, tzinfo=<DstTzInfo 'US/Eastern' EDT-1 day, 20:00:00 DST>)
df = DataFrame([{'End Date': dt}])
df
Out[26]: 
                    End Date
0  2012-06-01 00:00:00-04:00
df.dtypes
Out[27]: 
End Date    object
dtype: object
df_c = df.convert_objects(convert_dates=True)
df_c
Out[29]: 
             End Date
0 2012-06-01 04:00:00
df_c.dtypes
Out[30]: 
End Date    datetime64[ns]
dtype: object
```
