CFY-783 re-enabled cancel_workflow
Merge branch 'develop' into feature/CFY-783-add-support-for-cancel-execution
CFY-783 added limitation to cancel execution call; refactored execution statuses
CFY-783 merge commit
CFY-783 refactored rest service exceptions
CFY-783 added integration tests for cancel execution; added return statements for all currently existing  workflows so they propagate a 'execution cancelled' result if needed
CFY-783 renamed cancel_workflow into cancel_execution; added doc for this method in blueprints_manager
CFY-783 added documentation and more unit tests for cancel execution
CFY-783 added another integration test for cancel execution
CFY-783 modified travis.yml for tests
CFY-783 modified travis.yml for tests
CFY-783 modified cancel execution integration tests to use unique blueprint and deployment ids
CFY-783 flake8 fix
CFY-783 fixed travis.yml
CFY-783 reverted travis yml back
Merge pull request #54 from cloudify-cosmo/feature/CFY-783-add-support-for-cancel-execution

Feature/cfy 783 add support for cancel execution