In test file, forgot that last message sent in sequence (if not on
root event beginner), must send a "sequence completed" message back to
endpoint so that other endpoint can continue event execution.  Added a
method to context to handle this, with an explanation of purpose as
well as added a call to this method in test code.  Test case still
fails, but failure is further into execution.
Had a bug in which was using a random uuid for partner endpoint uuid
instead of actual uuid.  Fixed.
Fixes a bug: partner was returning to root that it should wait on
itself to complete the commit.  Root had not already added itself to
list of endpoints no longer have to wait for first phase commit on.
Added partner test to list of canonical locked tests.
Also unblocking waiting message queues on backout.