Add commands to pull translation from transifex

tx - transifex cli client should be installed in the system.
It's free software and is available in Debian archive.

Run following commands:
1. Init your authorization token
$ make transifex_init

2. Pull translations
$ make transifex_pull

Beremiz's user manual
=====================

Contents:

.. toctree::
   :maxdepth: 2

   install
   start
   edit
   build
   connectors
   debug