Use heat's default value for max_template_size

Instead of aligning value with tempest, make tempest use heat's default
value as that is what most people will be deploying with.

Change-Id: I77549f2b5e953ff712c50a2b372f6b04725d5eb0
Cleanup unused settings, use interface_driver setter

* Remove unused MIDONET specific settings from nova.conf
* Remove unused MIDONET specific settings from dhcp_agent.ini
* Move the interface_driver settings to the proper setting
  function so that it can be used by lbaas_agent.ini as well.

Change-Id: Id686ff5f55db00bce42b8a2bd56e7655c73211fb
Closes-Bug: #1245401
removed unecessary lines for docker install

* script was trying to copy file from a source
	that doesn't exist to destination that does.
* variable DOCKER_BRANCH no longer used.

Change-Id: I50fd55e97dfc4eaaa3c1f2bfc42e8cfc0e76cdf4
Merge "Cleanup unused settings, use interface_driver setter"
Merge "removed unecessary lines for docker install"
Merge "Use heat's default value for max_template_size"
Merge branch 'master' of github.com:openstack-dev/devstack