Fix bug 1028: Don't ignore exception in prepareInternalNetwork

As detailed in bug 1028, don't ignore the exception from
createIntegrationBridge as calling initializeFlowRules will fail.

Change-Id: Id0af4621667ac47d7f411645ea4df0d99f8d00cf
Signed-off-by: Dave Tucker <djt@redhat.com>
Merge "Fix bug 1028: Don't ignore exception in prepareInternalNetwork"