Add postal code format for France

Very straightforward. French postal codes consist of 5 digits only. Optionally, the first two digits can be separated from the next three digits with whitespace. [Data from Google](http://i18napis.appspot.com/address/data/FR). 

__Proposed format__
`^\\d{2}[ ]?\\d{3}$`

__Examples__
- 33380
- 34 092