mGerrit: Don't reload cards from network on Orientation change

We cache the raw json in SharedPreference and if our activity
is drawn because of Configuration change (orientation change)
we use our cached result

Thanks Splaktar for point this out.
(https://github.com/JBirdVegas/external_jbirdvegas_mGerrit/issues/1)

Change-Id: Id57610ba6f1af3531154748723924e05c214a46a