New: Collection Model, View, Templates, Serializers

Added new versions of old corpora MVC using collections.
Added: Foreign Relations with Collections

Added to piece/movement views, serializers, templates, the search templates, admin view, and urls.py.
Added: Collections in Solr

Added collection names for indexing pieces/movements; schema updated to reflect this change.
Added: Collections to dump_drupal.py

Needs to be tested, but dump_drupal should now copy corpora to collections
Added: Collections to solr_index.py

Needs to be tested, but now should index collections and pieces/movements manytomany collections.
Fixed: Bugs with importing collections

Removed typos and corrected syntax
Added: Collections to facets

Now can filter through collections in facets side-bar