Display local time instead of UTC in DatetimeIndex.__repr__
```
In [33]: rng
Out[33]: 
<class 'pandas.tseries.index.DatetimeIndex'>
[2010-04-13 00:00:00, ..., 2012-03-06 00:00:00]
Length: 100, Freq: W-TUE, Timezone: None

In [34]: rng.tz_localize('US/Eastern')
Out[34]: 
<class 'pandas.tseries.index.DatetimeIndex'>
[2010-04-13 04:00:00, ..., 2012-03-06 05:00:00]
Length: 100, Freq: W-TUE, Timezone: US/Eastern
```
