Refactor specs. Move TestHelper include to spec_helper.rb
Remove unused sample documents
Refactor CatalogControllerSpec to not use instance variable constants
Merge pull request #875 from projectblacklight/refactor_specs

Refactor specs
Add Blacklight.secret_key for encrypting and signing Blacklight messages

- under Rails 4, this defaults to the secret_key_base and requires no
  additional action.

- under Rails 3, this must be explicitly set. An example initializer is
  provided.
Add Document#exports_as? for checking if a document has the given export format
Add endnote and refworks export to the bookmarks tools.

Add endnote link to bookmarks tools iff at least one doc has
an endnote export.

Add the refworks link using an encrypted callback url