Merge pull request #635 from VictorLowther/pull-req-master-07cd2da2c693f3f87b4152996b7da62491f566ac

mighty fine!
Add a field for indicating what role implements the jig on a node.
Add client_role method to the Jig class.

It is intended to look up what role (if any) must be present on a node
to let a jig do things to it.  The role in question must be implicit,
and cannot be implemented by the same jig it implements.
Add support for automatically binding jig client roles to nodes as
part of add_to_node_in_snapshot.
Move jig creation into barclamp import time.
Flatten
The script jig will be created at barclamp import time now.
Add script jig entry in crowbar.yml
Avoid recreating jigs on import.
Only allow roles with active jigs to be bound to a node.
Add a helper to determine whether a role can be added to anything.
Skip adding default roles that are not active to jigs.
Fix typo in barclamp.rb
Fix typo in role.rb
Fix logic in barclamp.rb to not die if there is no jigs section.
Make role.rb work properly again.