Add a new variable 'kolla_devmode', which when enabled, clones and
bindmounts service source code into the containers.
This commit adds the relevant changes for Heat, more services can be
added and built upon.
Usage:
* Set 'kolla_devmode: yes'
* Code is cloned to /opt/stack/{{ project_name }} on target
node(s)
* Users can develop in these repos, and simply restart the container to
pick up / test changes.
Debugging can be done from the host via 'remote_pdb'[0].
[0] https://pypi.python.org/pypi/remote-pdb
Implements: blueprint mount-sources
Change-Id: Ic0431b10d723bf84eeefc72039376fe0058dd902
5cb375645c