2.2.1 dcaepolicyplugin and data types

2.2.1 dcaepolicyplugin and data types

- trying to avoid changing code for k8s deployment of
  policy-handler with unknown url to MSB or policy-handler
  at the moment
- expecting optional manual population of the consul-kv
  with config data for dcaepolicyplugin

- when not found service for policy-handler in consul
  -- try finding config for "dcaepolicyplugin" in consul-kv
  -- the config structure is expected to contain
      url to policy_handler
- example of config value for key=dcaepolicyplugin:
{
    "dcaepolicyplugin" : {
        "policy_handler" : {
            "url" : "http://policy-handler:25577"
        }
    }
}
- still drop down to hardcoded default when this config
   not found in consul-kv

- added and refactored unit tests for discovery -- coverage 78%
- making code more PEP8 compliant

Change-Id: Ia176b54ed62631baa30d614785d1937023408ddf
Signed-off-by: Alex Shatov <alexs@att.com>
Issue-ID: DCAEGEN2-419