Add rules and comments to .gitignore

* Defaults setted by the 'bundle gem' command
* Ignore environement swith files for Ruby version managers
* Ignore editors meta-data (RubyMine, Eclipse, SublimeText, TextMate)
* Ignore OS temporary files (Mac OS X, Windows, Linux)
* Ignore temporary or unwanted files
Do not insert locale params if already present in path

Add some logic in RouteTranslator::Translator.translate_path to detect if the locale param is present
in path. If not, locale is inserted at the beginning of the path as before.

This change let developper controls where he want the local param to appear and allow use of more
complex routing as `/:country/:locale/path/to/some/pages`.