Get rid of the magic we were using to bring up Chef.

This has several components:
  * Make chef-server and chef-client roles that the script jig handles.
    For now they are not configurable, but that will change.
  * Strip reliance on the Chef gems from the Crowbar barclamp.
    We now rely on shelling out to Knife for all our actions.  We can get
    away with that because we are no longer deeply entangled with Chef.
Add namespace extensions to allow the chef-server role to create the chef jig.
Merge pull request #54 from VictorLowther/pull-req-master-90ca95ce1c071c0e2bbb42c26ed6e3424e541022

https://github.com/crowbar/barclamp-chef/pull/54

Merged by devtool for VictorLowther