CIMI: Renamed 'name' attribute to 'key' in samples properties
CIMI: Removed 'context' from delete_attributes_for in Volume
CIMI: Improved 'store_attributes_for' to be more smart with properties

* In JSON the field is called 'properties', but in XML the XmlSimple parser
  call it 'property'. This patch will learn the store_attributes_for method
  how to deal with this.
CIMI: Add database support to Address entity
CIMI: Rename 'name' attribute in properties to 'key' in MachineTemplate
CIMI: Added AddressTemplate database model
CIMI: Added database support for managing AddressTemplate
CIMI: Added missing 'hostname' attribute to AddressTemplate