CFY-731 NOP task is no longer a singleton and NOP tasks are no longer filtered out - this is done so the user could still set dependencies on tasks which might be replaced with NOP tasks by us; Also, trying to create a dependency from or to a task which doesn't exist in the graph will now raise an error (before, it actually created new nodes in the graph)
CFY-731 flake8 fix
Merge pull request #10 from cloudify-cosmo/feature/CFY-731-modify-install-and-uninstall-wf-to-invoke-monitoring-interface

Feature/cfy 731 modify install and uninstall wf to invoke monitoring interface