Changes for server list
Changes to the resource listing command:
Added validate_params! method for default param checking code
Adding unit tests for resource listing
Modularized code for tests for resource listing
Updated tests for resource listing
Removed unwanted debugs
Removed unwanted TODO statement
Removed unwanted comments
Merge pull request #15 from opscode/adamed-oc-8822-server-list

OC-8822: Knife cloud openstack server list command