core: removing fenceSpmStorage verb and related classes

The use of fenceSpmStorage was removed in the previous patch in the
series, as it's not used anymore it can be safely remove along the
related classes.

Change-Id: I593a0620696729500d740c632a2a149c09366cbc
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1092752
Signed-off-by: Liron Aravot <laravot@redhat.com>