BUG date_range for Annual interval gives end of year instead of start
When Creating an Annual date range from the start of a year, the actual dates generated are for the END of that year, and do not include the datetime provided. You would expect to get a range starting from `start_date` and a series of subsequent dates one year apart

``` python
pd.date_range(datetime.datetime(2006, 1, 1, 0,0,0), periods=2, freq='A')

<class 'pandas.tseries.index.DatetimeIndex'>
[2006-12-31, 2007-12-31]
Length: 2, Freq: A-DEC, Timezone: None
```

For reference, using `dateutils.rrule` gives intuitive behavior

``` python
list(rrule(YEARLY, count=2, dtstart=datetime.datetime(2006, 1, 1, 0,0,0)))

[datetime.datetime(2006, 1, 1, 0, 0), datetime.datetime(2007, 1, 1, 0, 0)]
```
