Replaced `availiable_languages` by `note_languages`

`availiable_languages` have been a superset of all languages searchable and useable in note languages. The new implementation uses a configuration option `note_languages` for notes and a helper method `Iqvoc.all_languages` for search. The helper method returns an array of all languages configured anywhere in the instance by summing up all languages from pref_labelings, alt_labelings and notes.
Fixed whitespace
Merge pull request #184 from innoq/delete_availiable_languages

Delete `availiable_languages`configuration option