Add createStorageBusMonitor API point.  

See AppliedEnergistics/Applied-Energistics-2#418

Method returns "some IMEMonitor" guaranteed to get special treatment by the storage bus.  Allows external inventories to be implemented outside of the AE2 codebase and still cooperate with the storage bus.
The storage bus is coded for the ITEMS channel and IAEItemStacks only, so yeah I think even at an opaque level, that is correct.