Initial tests and model for Association Class
association class initial template
passing tests for Association Class, but need to fix problem in Big
class require missing.
Merge branch 'master' into class_association

Conflicts:
	acceleo/run_all_tests.sh
Tests Passing on Association Class, all functionality implemented
Refactoring association class
Merge remote-tracking branch 'origin/master' into class_association

Conflicts:
	acceleo/run_all_tests.sh
Merge pull request #94 from uiuc-cs428/class_association

Association Class