Set up a private key

This change modifies the CI script, so that it also requires a private
key file, and uses that key for the OpenStack installation.
Add SR replacement

Should the XenServer have a non-ext type SR, the devstack install script
can try to destroy the default SR, and replace that with an ext type SR
if the user specified the -f switch.
tempest-smoke.sh -> install-devstack-xen.sh

tempest-smoke.sh is the script that was ran by the CI system. This
change removes the old install-devstack-xen.sh script, and replaces that
by tempest-smoke.sh. This way people will run the same script that is
running in the CI.
Get rid of old ci scripts

This change removes the old scripts, that are no longer used.
Accept domain names for XenServer

As the old script did, the new script should also be able to use a
xenserver if that's specified by a domain name. The IP address will be
detected by looking up xenbr0's address.
Comment out FLAT_NETWORK_BRIDGE

As the change that enables to specify FLAT_NETWORK_BRIDGE hasn't landed
yet, it should be commented out from the official script, and used only
on the internal builds.
Merge pull request #17 from matelakat/unify-scripts

Unify scripts