Removed subactivity defining

Removed the defining of any behaviors (sub-activities) in the main
activity ruby output file, and added logic for require_relatives for
behavior actions
Fixed unit tests

Removed unneeded unit test from activity_node_test.rb, and updated one
unit test in call_operation_node_test.rb since I added a space around
the equals sign
Added unit tests for Big Activity Diagram
Merge remote-tracking branch 'origin/master' into Iteration6_BigActivityDiagram
pull in hollys changes