core: StoragePool equals problem

- On a blank default data center, showing the subtabs
  would cause the loading indicator to show every refresh
  period. This was due to an issue in the storage pool class
  that caused the equals to return false when it should be
  true. This patch fixes that issue.

Change-Id: I5ae44a6ea127b4e3b35647721fd2e927bac130b6
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1073041
Signed-off-by: Alexander Wels <awels@redhat.com>