bump file-server gunk

Submodule src/github.com/cloudfoundry-incubator/file-server 59397e5..e432c8a:
  > Replace http_client with inline versions
Submodule src/github.com/cloudfoundry/gunk 107fe13..8d0c836:
  > Remove http_client

Signed-off-by: Johannes Petzold <jpetzold@pivotal.io>
Merge remote-tracking branch 'origin/develop' into develop
bump auction gunk

Submodule src/github.com/cloudfoundry-incubator/auction 8fd6168..31931a3:
  > Use Close() instead of Disconnect()
Submodule src/github.com/cloudfoundry/gunk 8d0c836..4033c30:
  > Replace Disconnect() with Close()

Signed-off-by: Johannes Petzold <jpetzold@pivotal.io>
Create final release 0.481 for build 235