Chore/dependencies

@NYULibraries/hydra 

Updated dependencies:

* Bootstrap3
* Hydra 7 (w ActiveFedora 7)
* Blacklight 5+
* Ruby 2.1.3 - Note the bundle will not build on a ruby version < 2.0 as some of the gems require Ruby >= 2.0

Not-updated:

* Rspec
* Mustache

Major Hydra updates to note:

* There is only one `role_map.yml` file in Hydra 7 with entries for individual environments
* The `to_solr` method on `Nyucore` in combination with the `apply_prefix` method in `NyucoreDatastream` create somewhat of a hack in order to index all datastreams into the same prefixed `desc_metadata__` fields in solr. It used to work out of the box in Hydra but the method has been changed no longer making that a straightforward solution/
* The `map_predicates` syntax for RDF datastreams has been changed to `property :subject, predicate: RDF::DC.subject`. This is reflected in `NyucoreDatastream`