Use urandom for heat key generation

Reading from /dev/random can block an virtual machine
even for several minutes, when the entropy pool is empty at the read time.

I have doubts we really need to use /dev/random here.
Even the ssh-keygen uses /dev/urandom by default,
 so the /dev/random is a little bit overkill here.

Change-Id: I6d2c6364c2b445304a33b0140e3cdc6804404b63
Neutron.conf is not setup unless q-svc is enabled

In a multi-node environment, a node may have the neutron-
openvswitch-agent running but not the neutron API server.
The agent uses neutron.conf as one of the configuration
files. Devstack sets up neutron.conf only when q-svc is
enabled. Neutron.conf also needs to be configured when
q-agt is enabled.

Change-Id: I3d454caff0b49a61ee1a78f68b1bca98e29f21de
Closes-Bug: 1184064
download fedora x86_64 image if heat is enabled

clean up the logic around producing a valid cfn image for heat
testing. If heat is enabled, add the f20 x86_64 imageurl to the
list of images that we support, and set that as the tempest
orchestration image.

The crux of this change is left commented out for now because we
need a two phase update of nodepool content before we can move
away from the old image (otherwise fedora mirrors will kill us
with bad downloads).

Change-Id: I1da9f259a3267b1bd27e9899755204c8fff41153
Merge "download fedora x86_64 image if heat is enabled"
Merge "Neutron.conf is not setup unless q-svc is enabled"
Merge "Use urandom for heat key generation"