Add to 'make generate_locales' the generation of a
'transifex/messages.json' that will be automatically pulled by transifex
for translations.

To incorporate translations from transifex into our project we'll need
to manually download the selected translations and convert them with the
transifex program into gotext format.

-Resolves: #73

Using golang.org/x/text, wich is still in early stages of development,
but seems to work good enough for our needs.

- Resolves: #2