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

.project

.directory

syntax: regexp
^tests/.*/build$
^.idea/.*
syntax: regexp
^.*\.pyc$
syntax: regexp
^.*~$
syntax: regexp
^.*\.swp$

bug_report.*\.txt
i18n/.*.new$
revision

doc/_build
doc/locale