using backing datagrid: use SetFromLiveMap
added EntityDynamicType.FieldAndValue.toString
InternalLocationFactory tidying
Tidy AttributeMap.NULL marker object

- will be required soon for serializing!
Switch BrooklynStorageFactory for DataGridFactory
Location: store fields in datagrid

- and adds ManagementContextInternal.prePreManage
LocalEntityManager: store entity ids in datagrid
ConfigBag backed by datagrid
LocalLocationManager: backed by datagrid
Fix resolver tests for location.name
Cleanup AbstractLocation.addChild

- temporary badness of some commented out code
Datagrid work: incorporate review comments
Merge pull request #1078 from aledsage/fix/storage-picking-from-other-branch

storage-related changes