sparts.collections.UniqueQueue

Add a UniqueQueue subclass of Queue for keeping track of lots of things
and silently discards duplicates.
UniqueQueue should track discards

A basic counter for tracking purposes
sparts.tests: all warnings raised during unittests should fatal
sparts.thrift.client: Use non-deprecated API for THTTPClient
Render ipv6 `host` values correctly for THttpClient

Update the getConnectURI method for the thrift client to properly render
host values that are v6 addresses.

Updated the fb303 unittest to catch this and verify the fix.
Prefer HAS_THRIFT from sparts.deps