Investigate failing integration test runs

Investigate whether recent changes/additions to TestChangesAdminChannelGrantLongpollNotify, TestIncludeDocsWithPrincipals are related to the Couchbase Server timeouts we're seeing in TestDocumentNumbers on master.  

Should run the integration suite with these tests disabled to see whether they are in fact the root cause, and if so, dig into why.

Similarly, could try running with previous master commits (December, January?) to identify whether it's a current environment issue, or something that's changed in the code.