Rename t_storage to atom_storage
Rename t_storage to atom_storage

This name reflects better what the storage module is
actually being used for/does. The prior name was not
very informative and meaningful.

Part of blueprint plug-engine

Change-Id: I7015620f5536fc766cff3a877edd0e94d25db1ed

junneyang/taskflow,pombredanne/taskflow-1,jimbobhickville/taskflow,openstack/taskflow,jimbobhickville/taskflow,pombredanne/taskflow-1,junneyang/taskflow,openstack/taskflow