add getFullyStarted() to OpenFlowPluginProviderImpl
and fix the order of isOnlineFuture vs readyRunnable: For a test to be
able to await getFullyStarted() and then check diagstatus, that
(diagstatus) needs to be set BEFORE, otherwise there is a race
condition.
This has come up while writing the testDiagStatus() for the
OpenFlowPluginWiringTest for opendaylight-simple.
JIRA: OPNFLWPLUG-1061
Change-Id: Ic9b5f9b49038fa75451e81ebaa1e6fbdbc41c683
Signed-off-by: Michael Vorburger <vorburger@redhat.com>