* Add 2.0.0 changelog
* Update DMSInterface and DMSDocumentInterface removing *page and adding getDocumentSetsByPage to DMSInterface
* Update use documentation and update unit tests
This commit changes the relationship from Pages has_many Documents to Pages has_many DocumentSets which are many_many to Documents. The upload field has been upated to attach documents to a set instead of a page, the tests updated and the DMSInterface and DMSDocumentInterface updated to be less relevant to pages and more relevant to document sets.
