Merge into master from pull request #23:
OFStateManager flowtable cleanup (https://github.com/floodlight/indigo/pull/23)
OFStateManager: do not maintain a list of output ports

The out_port metamatch check can be done using the actions/instructions list.
This saves about 2% RSS for an IVS with a full flowtable.
OFStateManager: remove use of flow_add from flow stats handler
OFStateManager: remove use of flow_add from flow removal
OFStateManager: remove use of entry->flow_add from ind_core_ft_iter
OFStateManager: remove flow_add from flowtable entry

This saves about 18% RSS for an IVS with a full flowtable.