Create locales.js.erb - Now the locales are accessible to JS

Some JS files (like bookmark_toggle.js) have locales strings inside them, this causes 2 problems:
1) Changing to another language won't work (for the locales strings that are in bookmark_toggle.js).
2) The locales are scatterd around the project instead of one place.

Now the locales which are used from ruby are also used from Javascript.