Chef

Move  'isURL' function. I think it must be defined always, not only for Red Hat.
Add two usefull custom commands: "runApply" that call chef_apply, and "rerun" that rerun chef-client.
Save runParams in Cloudify attributes. So the user can create a custom command to update the chef configuration dynamically.
Move the recuperation of Chef server url earlier. In case of misconfiguration we want fail asap. And we check the configuration file in the case where Chef server is not deployed by Cloudify.