Cache more stuff into image

This loads more stuff into the image at
time of build, rather than having devstack
install these upon run.

The goal is to make the image independent of
most external network dependencies.
Cleanup and reorder dockerfile

Also changes how we set the docker apt repo
Add separate tempest start script and image

Creates a dockerfile specific to tempest runs,
adds tempest stuff to the base dockerfile as well
(tempest gets installed for interactive runs, it just doesn't run
as a CMD)
Cleaner prereq install - install tempest pip reqs

Use devstack's prereq install script instead of hard-coding in
all of the debian packages! This is a lot cleaner!

While tempest pip reqs should be included already in
global-requirements, it seems there must be an upstream bug.
This works around that.
Move dockenstack scripts into dockenstack dir
Discard docker stdout/stderr
Use entrypoint for tempest, allow arbitrary args
Support arbitrary git repos for nova
Remove devstack-extracted package installs - now redundant
Fix location of devstack clone
Update README
Fix fixes to README
DIY init scripts

Creates a devstack-init script which "start" and "tempest" run.

Also creates a localrc.d directory.
Add STABLE_RELEASE env var
Force HOST_IP_IFACE=eth0
Checkout appropriate devstack for STABLE_RELEASE
Re-add 'start' script
Fix devstack-init perms
Update Maintainer
Fix path for localrc.d