CFY-1808 cancel execution REST request will now be replied with 200 on success rather than 201
CFY-1808 added a test for legacy cancel execution
CFY-1808 modified rest service dev-requirements for travis
CFY-1808 modified legacy cancel execution test's workflow; fixed REST service tests
Merge pull request #184 from cloudify-cosmo/CFY-1808-cancelled-execution-shows-up-as-terminated

CFY 1808 cancelled execution shows up as terminated