Suggest using ISO 8601 for display of Period and PeriodIndex
As of pandas 0.8.1, the Period and PeriodIndex display uses the English abbreviations for the month.  Suggest that ISO 8601, would be a better choice.

Annual Period is fine...

> z =PeriodIndex([Period('2012'), Period('2013')])
> 
> z
> Out[182]: 
> <class 'pandas.tseries.period.PeriodIndex'>
> freq: A-DEC
> [2012, ..., 2013]
> length: 2

Monthly though...

> In [185]: z =PeriodIndex([Period('2012-01'), Period('2012-02')])
> 
> In [186]: z
> Out[186]: 
> <class 'pandas.tseries.period.PeriodIndex'>
> freq: M
> [Jan-2012, ..., Feb-2012]
> length: 2

I think that 'z' instead should be:

> In [186]: z
> Out[186]: 
> <class 'pandas.tseries.period.PeriodIndex'>
> freq: M
> [2012-01, ..., 2012-02]
> length: 2

Hourly currently is

> z =PeriodIndex([Period('2012-01-01 00', freq='H'), Period('2012-01-01 01', freq='H')])
> 
> z
> Out[193]: 
> <class 'pandas.tseries.period.PeriodIndex'>
> freq: H
> [01-Jan-2012 00:00, ..., 01-Jan-2012 01:00]
> length: 2

The ISO 8601 standard representation of hourly Periods would be:

> In [186]: z
> Out[186]: 
> <class 'pandas.tseries.period.PeriodIndex'>
> freq: M
> [2012-01-01 00, ..., 2012-01-01 01]
> length: 2

Advantages:
Not English centric
Directly sortable chronologically without parsing

Kindest regards,
Tim
