BUG/API PeriodIndex handles int list/array differently 
When we pass a list of numbers, it parsed as date as it is. The same values is regarded as `ordinal` if it is passed as an array.
#### Code Sample, a copy-pastable example if possible

```
raw = [2005, 2007, 2009]

pd.PeriodIndex(raw, freq='A')
# PeriodIndex(['2005', '2007', '2009'], dtype='period[A-DEC]', freq='A-DEC')

pd.PeriodIndex(np.array(raw), freq='A')
# PeriodIndex(['3975', '3977', '3979'], dtype='period[A-DEC]', freq='A-DEC')
```
#### Expected Output

Because `PeriodIndex` has a `data` and `ordinal` arg, it should be regarded as:
- date if it is passed via `data` kwd
- `ordinal` if it is passed via `ordinal` kwd
#### output of `pd.show_versions()`

on current master.
