Added a test case to stress passing single thread variables in a variety of ways.
Simple .gitignore for emit_tests because I was sick of all the untracked emitted files for runAllTests being shown with using git status.
Fixes ugly bug: get_and_remove_event expects remove_event_if_exists to
return a value (the event if it exists or None if it doesn't).  By not
returning anything, was always returning None.  This interfered with
propagating backout messages: when servicing a
_ReceiveRequestBackoutAction, would always get no event, and not ask
that event to forward on the commit.
Removed unnecessary spacing per (Python style guide)[http://www.python.org/dev/peps/pep-0008/].
changed emitted 'pass' on backout exception to 'continue'. Theoretically an improvement.
Merge branch 'master' of github.com:bmistree/Waldo into bug_test
Merge branch 'bug_test' of github.com:bmistree/Waldo into bug_test