Remove remaining references to `api_version`

* This is hardcoded now; please see
  https://github.com/cloudfoundry/cloud_controller_ng/commit/353149689f680dde6f8a67ee015dabd3ee1f9e9b
  for more info

[delivers #67804418]

Signed-off-by: Abhijit Hiremagalur <abhi@pivotallabs.com>
Bump src/cloud_controller_ng

Bump cloudfoundry/cloud_controller_ng:
  Chris Adams:
     Add an endpoint to restage the app ( Travis created: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/23230972 )
  Phan Le:
     Trying to fix a flakey test. ( Travis Success: https://travis-ci.org/cloudfoundry/cloud_controller_ng/builds/23220270 )

Signed-off-by: Kai Zhang <kaizhang@cn.ibm.com>