Bump src/gorouter, src/hm9000

Bump :
  Luan Santos and Graeme Davison:
     Use Apcera's yagnats
     Update godeps
Bump cloudfoundry/hm-workspace:
  Luan Santos and Graeme Davison:
     Add apcera/nats as a test dependency of hm9000 on .travis.yml ( Travis Success: https://travis-ci.org/cloudfoundry/hm-workspace/builds/35586943 )
  Graeme Davison & Luan Santos:
     Update yagnats related submodules ( Travis Failed: https://travis-ci.org/cloudfoundry/hm-workspace/builds/35586313 )