website: remove deprecated observers

Rails 4 has removed the Observer class. Instead we should create a
concern with after_save and before_save methods for performing actions.
website: update recaptcha initializer to new format
website: remove forced development environment
website: implement searching inside database

Search results from backends are now saved in the database. If the
same search query is executed within a week the search controller
will instead search the database instead of the backends. This should
speed up searching and minimize our requests to the various APIs.

The database searching is powered by Solr via the Sunspot gem.
website: remove unique constraint on foreign url on sources
website: use proper helper methods instead of transforming string manually
translation: add tooltip for Balog Tamas in credits
website: add test for bug in song title parsing
website: fix bug in song title parsing
website: move code from search controller to model
website: add ability to find event by its source
website: add ability to find artist by its source, and make name matching case insensitive
website: add ability to find album by its source
website: move css styles for alerts and notices
website: add ability to create source using a hash instead of path
website: make search controller functional

Make the search controller fetch results from backends if the search
query is fresh (not made within a week). Then use Solr (via Sunspot)
to fetch query the database for the final search results.
.gitignore: ignore the solr folder
website: refactor image code into concern
website: add partial views for viewing models inside lists
website: make list items at least 64 pixels high