babel: translation loading from PACKAGES

* Adds lookup for '/translations' directory inside defined `PACKAGES` in
  order to support custom translation strings.  (addresses #828)

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>
babel: setuptools integration

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>
encoder: fix encoding of websubmit.js

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>
installation: automatic catalog compilation

* Adds automatic catalog compilation before build and installation
  command.

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>