[FrameworkBundle] translation:update improvements

Bug fix: no
Feature addition: yes
Backwards compatibility break: no
Symfony2 tests pass: yes
Fixes the following tickets: -
Todo: -
License of the code: MIT
Documentation PR: -

added namespace support

added common-catalogue option

now finds the translation token in twig and php files, plus extracts form labels

added form-label-fallback option, if no label is specified, it falls back to the name attribute (or what is specified eg.: id)

added headers for PO files, set encoding