core: Support format option for data domain

Adding the option to remove Data Storage Domain from the engine without
formatting it so we can use it to move entities from one setup to
another.

Change-Id: I4392de431f6523e3824bbddd9d79aa4b1eb0819c
Bug-Url: https://bugzilla.redhat.com/1138132
Signed-off-by: Maor Lipchuk <mlipchuk@redhat.com>