Consolidate config into single file

Upstream commits [1,2] modified heat to use a single config file.
This modifies the puppet config of each component to use different
sections of the same file.

Some notes about the change:

 - each of heat-api, heat-api-cfn, heat-api-cloudwatch has indvidual
   options for bind_port, bind_host
 - heat-engine options live under DEFAULT (it does not bind to any
   ports)
 - new log_dir global
 - slight fixes to ENCRYPTION_KEY generation for new heat.conf name
 - include rspec tests for api-cfn & api-cloudwatch

Fixes bug 1214824

[1] https://review.openstack.org/#/c/39980/
[2] https://review.openstack.org/#/c/43697/

Change-Id: I7d8865a809da71696b944ab0654a1f728cd827df