add serbian (rs) locale
renaming back ukrainian locale to 'uk', as 'ua' doesn't exist in select2 repo and it's causing fetch task to crash.
update select2 assets to last version
Merge pull request #83 from p-lambert/select2-update

Assets update and serbian locale addition
update version 3.5.5 - select2 3.4.6.
update version 3.5.6 - select2 3.4.7.
update version 3.5.7 - select2 3.4.8.
Merge branch 'master' of https://github.com/argerim/select2-rails

Conflicts:
	app/assets/javascripts/select2_locale_ka.js
	app/assets/javascripts/select2_locale_rs.js
	lib/select2-rails/source_file.rb