Added Hosts list for Rack
Renamed 'Host' to 'Node'
Replaced 'node_url' with 'node_id'
Added ironic_url configuration variable
Replaced chassis_url with chassis_id
Merge pull request #7 from mfojtik/rack_hosts

Added Nodes list for Rack
Updated Resource Class API

Add transactions to the database operations
Add GET and DELETE operations
Support association of Racks in POST operation
Starts work on nested marshalling