Implementations of dpa api #234

Hello,

I would implement dpa api, should I download the indigo_submodule_automerge branch? Cause I have noticed that in the master branch some APIs missed, like indigo_fwd_add_flow().
I have a Cisco Catalyst switch that does not support Open Flow, so I would use the Indigo agent and to communicate with the Switch I thought about using Telnet.