Adding check for existing destination of a MOVE, and adding IT to check it
Also fixing COPY method
Add integration test for testing CRUD concurrent performance with up
  to 32 threads.

Resolves: https://www.pivotaltracker.com/story/show/70724622
PUT requires either new resource or RDF to update properties, adding ITs for PUT and POST/slug to existing resources
Trying to create an existing workspace now results in 409 Conflict
Adding error handling for invalid CND updates
Restoring item with same UUID as existing node returns 409 Conflict
Handling invalid namespace creation error
Merge pull request #369 from fcrepo4/workspace-existing-conflict

Trying to create an existing workspace now results in 409 Conflict
Merge pull request #370 from fcrepo4/nodetype-errors

Adding error handling for invalid CND updates
Merge pull request #368 from fcrepo4/move-to-existing

Adding check for existing destination for COPY, MOVE, PUT and POST w/slug
Merge pull request #371 from fcrepo4/restore-conflict

Restoring item with same UUID as existing node returns 409 Conflict
Merge pull request #372 from fcrepo4/namespace-errors

Handling invalid namespace creation error
Handle errors for trying to list version of unversioned node

Resolves: https://www.pivotaltracker.com/story/show/71705296
Address checkstyle issues in preparation for tighter enforcement

Resolves: https://www.pivotaltracker.com/story/show/71267176