Bug: Fixed Issue 2993, Incorrect Timestamp Construction by datetime.date and tz
`Timestamp` cannot be constructed correctly by given an `datetime.date` instance and `tz`.
The issued has been solved in this patch and the test case is add in `pandas/tseries/test/test_timezones.py`

Looks fine to me.

Please setup travis to make sure all the tests are green, and I'll merge this.

``` python
In [15]: d=datetime.datetime(2013, 3, 9)
    ...: print pd.Timestamp(d.date(),tz='US/Pacific')
    ...: print pd.Timestamp(d,tz='US/Pacific')
    ...: 
2013-03-08 16:00:00-08:00
2013-03-09 00:00:00-08:00
``
```
 look ok to me 2
 The Travis build passed.
 Merged. thanks for contributing.
