Merge branch 'release-1.2.0'
multiprocessing.Queue has no `task_done()`

See https://docs.python.org/2/library/multiprocessing.html#pipes-and-queues

Specifically:

"The Queue, multiprocessing.queues.SimpleQueue and JoinableQueue types are multi-producer, multi-consumer FIFO queues modelled on the Queue.Queue class in the standard library. They differ in that Queue lacks the task_done() and join() methods introduced into Python 2.5’s Queue.Queue class."
Added unit-test for complete linkage.
single-linkage test less prone to alg. changes.
Added unit-test for uclus linkage.
Added a unit-test for UCLUS linkage.
Merge remote-tracking branch 'loisaidasam/master' into release/1.2.1
Added unit test for multiprocessing.
Version bumped to 1.2.1
Merge branch 'release/1.2.1' into develop