bump bbs
bump bbs

Submodule src/github.com/cloudfoundry-incubator/bbs e48b28c..01a1e3f:
  > Set etcdClient consistency to strong on integration tests

cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release