Swordtesting

 * Add and update some sample documents in the RestTesting directory, and update rest testing documentation.

 * Add license headers to everything in the CRUD bundle.

 * Add ContentBuilder and DepositBuilder for creating entities from SimpleXML.

 * Add exceptions to the SWORD bundle, to make error handling much much easier. They are caught in the SWORDErrorListener which produces appropriate SWORD error documents.

 * Refactor the SWORD controller and add tests, update the twig files as needed.

 * Add a Namespaces class to make dealing with namespaces in SimpleXML less painful.

This PR may require a schema or composer update. It also relies on changes in PR #12 which should probably be merged first.