Generate .po and .pot files with android2po.

See
https://github.com/miracle2k/android2po/blob/master/README.rst

This is useful to some translators.
Import translations from .po files with android2po.

The changes are just formatting, but doing this will make it easier
to see real changes next time.
Add the android2po configuration file.

So we can just do
a2po init
a2po export
a2po import