Refactor Translator JS

Fix #23
Fix #25
Refactor controller/dumper and JS

* JS now implements the Symfony TranslatorInterface
* Ability to get translations for a set of locales rather than only one,
  for a given domain
* Better dumper: dumped files don't contain the configuration, and a
  special `config.(js|json)` file is generated
* The route pattern has been changed
* More tests
* Rename templates
* Remove `defaultDomains`
Rename bundle

Fix #79
Fix #81
Recompile JS
Fix command
Set minimum Symfony version to 2.3
Fix naming
Merge pull request #82 from willdurand/refactoring-v2

Refactoring v2