update indigo

* submodules/indigo 4ce611c...88cdd3a (3):
  > Merge into master from pull request #98: OFConnectionManager: fix disconnection of listen connections (https://github.com/floodlight/indigo/pull/98)
  > Merge into master from pull request #99: add role to debug's (https://github.com/floodlight/indigo/pull/99)
  > Merge into master from pull request #97: prepare ofaux for switchlight integration (https://github.com/floodlight/indigo/pull/97)
Merge into master from pull request #124:
update indigo (https://github.com/floodlight/ivs/pull/124)