* adds test for duplicate names and ids for backends
* also adds test for rename duplicates and changing ids
* makes kvs backend raise an exception if duplicate is requested
* ensures kvs backend doesn't allow update of id
* makes sure that kvs is reset between tests
* cleans up a few imports
* fixes bug 927291
* fixes bug 928659
Change-Id: Ia6eb1961796cbde7ed57a75cd9394d77c88cf655