core: Changed master connection type in RecoveryStoragePool command

As a part of the effort to remove the type of storage pool, this patch
makes the RecoveryStoragePoolCommand use the storage helper of the type of
new master when connecting to the new master.
Until now the old master type was used since it didn't make any difference
since the types of the old and new were always the same

Change-Id: Ifb0b0f98bdd239f201add78b08e8c1f86cf84757
Relates-To: https://bugzilla.redhat.com/1038053
Signed-off-by: Tal Nisan <tnisan@redhat.com>