issue #242: Do not allow user deactivate/delete storage pool used by a template

Make a integrity verification when user try to deactivate or delete a pool.
If pool is used by a template it should not be deactivated or deleted to
avoid problems while using the template.
Also update the po files as new messages are added to alert the user.

Signed-off-by: Aline Manera <alinefm@br.ibm.com>