dereference instance not thread-safe
Fixed QuerySetNoCache.count() caching (#410)
Merge remote-tracking branch 'origin/pr/412' into 412

Conflicts:
	AUTHORS
Fixed dereference threading issue in ComplexField.__get__ (#412)
Updated docs about TTL indexes and signals (#413)
Fixed indexing - turn off _cls (#414)
Update transform to handle docs erroneously passed to unset (#416)
Added regression test (#418)
Fix test