Created a policy_delete command.  Nodes now have a 'bound' field in the database that
in the absense of a policy associated with the node will force a noop installer causing
a local boot.  An unbind will now clear any policy and set bound to false.
find_by_name method for policy
find_by_name needs to be a class method
patching up around db constraints
find the noop installer properly
repo.url shortcut to repo.iso_url
Merge branch 'master' of https://github.com/puppetlabs/razor-server