update indigo

* submodules/indigo 2e7089b...0156ec8 (3):
  > Merge into master from pull request #118: OFConnectionManager: batched message processing (https://github.com/floodlight/indigo/pull/118)
  > Merge into master from pull request #120: SocketManager: restrict priority range (https://github.com/floodlight/indigo/pull/120)
  > Merge into master from pull request #119: OFConnectionManager: populate auxiliary_id field in controller connections reply (https://github.com/floodlight/indigo/pull/119)
Merge into master from pull request #145:
update submodules (https://github.com/floodlight/ivs/pull/145)