adds i18n-js gem providing us with easier access to translations in js
some cleanup of changeset css. once again, revisions are on the same level as history in issues/show
Making i18n-js work for OpenProject

* Limit i18n keys in JS to the 'js' scope to reduce payload
* Update i18n gem to make i18n-js work with limited scopes
* Exporting translations on server start and not on every request to save
  computing resources and avoid impact on response times
* Configuring i18n-js to use the same fallbacks like the ruby part to ensure
  consistent behavior across languages
* Removing rake tasks from Rakefile since (a) they do not belong there - should
  have been in lib/tasks - and (b) they are no longer needed, since the export
  happens at server start

NB: public/javascripts/i18n needs to be writeable by the app server user.
Simplifying loading of Gemfile.local and plugin Gemfiles
Merge pull request #49 from finnlabs/chiliproject

CSS fixes to show revision at the same level as history
switch from chosen to select2

Conflicts:

	app/helpers/application_helper.rb
	app/views/layouts/base.rhtml
	public/stylesheets/project_select_select2.css
working project selection with updated select2

Conflicts:

	public/stylesheets/chosen.css
traps mouseevents inside top level menu items
update select2 css to current master 222fa7e4
one more open/closed event trigger for the top level menus on 'enter'
simulate tabbing away from select2 project search
remove fixed height for select2 boxes
simulate tabbing to select2 input field inside projectsearch
prevent ESC from closing project search menu
move select2 customizing stuff to select2_customizing.css
bump select2 version to current master; fixes tabbing issues
update select2 version and cleanup
removes leftover chosen.js

Conflicts:

	public/javascripts/chosen.js
Cleanup select2 adaption stylesheet

Removing unused rules, updating colors to latest theme, changing look to better
match previous project list
Cleaning up top_menu_helper

Removing unused parameters, simplifying code