Deleted TEMPDIR on exit

To avoid undeleted tmp.XXXXXXXXX directories left in /tmp, and output
unified style patch for later apply.

Change-Id: I6069c3cf36e345e5101ae3cf884e647c1d42030e
Make LoadBalancer nested stack template configurable

Reviving work originally posted by Angus Salkeld under
https://review.openstack.org/#/c/21405/

This is to enable the various distros to easily override the
hard-coded default nested template (which currently only supports
Fedora 17) with a template approporate to their distro, and
enables deployers to specify their own template (although the
latter use-case will probably be catered for via a provider
template implementation long-term).

Change-Id: I0a4eccb23b2eebbf31b7aabf0fe85ab31f0ca971
Partial-Bug: #1234375
Co-Authored-By: Angus Salkeld <angus@salkeld.id.au>
Merge "Make LoadBalancer nested stack template configurable"
Merge "Deleted TEMPDIR on exit"