As python 2.x support is ending with 2019, all DCAE components should be migrated to python 3.x.

This impacts Cloudify, plugins + other dcae platform component (relates to DOC-419)

1. Convert our code to be compatible with Python 3.x. (For example, using “import future” and making certain that loops work on iterators instead of lists when the API calls return iterators in 3.x.)
2. Set up our plugin tox tests so that they are executed with both Python 2.7 AND Python 3.x.
   1. Upgrade all plugins (k8splugin/dmaap/policyplugin/relationship/postgres/helm) to support both 2.x and 3.x - Tony/Jack
   2. Verfiy all other components (CBS, PH, SNMP trap, Heartbeat)
   3. Policy library (utils) - Alex
   4. MOD - DistributorAPI, OnboardingAPI, Acumos Adapter (Frankfurt addition)
      ## PMSH (Frankfurt addition)