ValueError: Cannot compare tz-naive and tz-aware timestamps
Trying to generate a time series based on timezone raises exception.

```
>>> import pandas
>>> pandas.date_range('2013-01-01T00:00:00+05:30','2014-03-07T23:59:59+05:30',freq='AS')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/cruiser/work/metroleads/lib/python2.7/site-packages/pandas/tseries/index.py", line 1794, in date_range
    closed=closed)
  File "/Users/cruiser/work/metroleads/lib/python2.7/site-packages/pandas/tseries/index.py", line 196, in __new__
    infer_dst=infer_dst)
  File "/Users/cruiser/work/metroleads/lib/python2.7/site-packages/pandas/tseries/index.py", line 406, in _generate
    index = _generate_regular_range(start, end, periods, offset)
  File "/Users/cruiser/work/metroleads/lib/python2.7/site-packages/pandas/tseries/index.py", line 1750, in _generate_regular_range
    dates = list(xdr)
  File "/Users/cruiser/work/metroleads/lib/python2.7/site-packages/pandas/tseries/offsets.py", line 1871, in generate_range
    if periods is None and end < start:
  File "tslib.pyx", line 611, in pandas.tslib._Timestamp.__richcmp__ (pandas/tslib.c:10872)
  File "tslib.pyx", line 640, in pandas.tslib._Timestamp._assert_tzawareness_compat (pandas/tslib.c:11186)
ValueError: Cannot compare tz-naive and tz-aware timestamps
```

```
pandas==0.13.1
```
