Remove instructions to pull patch for x86_64 to create-nodes

The needed patch has been merged, so we don't need to pull it in
manually anymore. Instead we update LKG to include it.
Merge pull request #36 from gfidente/x86_64

Remove instructions to pull patch for x86_64 to create-nodes
Add support for tripleo packages

If instack-undercloud is installed from package, other tripleo packages will be
used. If run from git, then other tripleo projects will also be used from
source.

The behavior can also be controlled via $INSTACK_TRIPLEO_SOURCE
Set INSTACK_ROOT for the packaged install
Make sure $NETWORK_JSON is defined.
Remove specfile and building instrcutions, the source is now maintained in dist-git exclusively