Basic handling of locales.

Module to implement basic handling of locales as requested in issue #5314. It accepts locales when given in the form of `en_US.UTF-8`. Creation and removal of locales is handled via locale-gen.
So far I have only tested/used the module with Debian 7.

Note that I'm only aware of Ansible since yesterday evening so I may well have missed some existing building blocks. If this is the case, please point me to common building blocks (such as file manipulation and process handling).