Merge into master from pull request #178:
update submodules (https://github.com/floodlight/ivs/pull/178)
update loxigen-artifacts

* submodules/loxigen-artifacts eb1f96d...c5aa7c7 (3):
  > Artifacts from https://github.com/floodlight/loxigen/compare/0377adb1d21737eba2604864a4913894e8f5fc9f...f2de8afd2bf6daddf31a52a459737889aea0e4bb
  > Artifacts from https://github.com/floodlight/loxigen/compare/a6678c76b234bce89ba2054a6ee90d0b7e50db61...0377adb1d21737eba2604864a4913894e8f5fc9f
  > Artifacts from https://github.com/floodlight/loxigen/compare/d4a45c841e8d6dc5cd3ca9ed5e56fcb14cd2a591...a6678c76b234bce89ba2054a6ee90d0b7e50db61