Replaced shebangs with /usr/bin/env call

This way the environment can decide which interpreter got to be used. It's absolutly usefull if we try out other ruby versions or to use another path for the ruby binary.
Removed locale_additions functionality

As the i18n content is now always stored within the localization files we don't need the locale_additions anymore. And of course we don't need this extraction methods either.
Use correct command line

Use the correct command line instead a shortcut that will be removed in
a future version within another commit
Added copyright to generated navigation
Added single link for primary menu entries
Merge pull request #2035 from tboerger/feature/cleanup

Cleanup backported from rails4 branch