Bump src/collector

Bump cloudfoundry/collector:
  Maria Shaldibina:
     Bump vcap-common ( Travis Success: https://travis-ci.org/cloudfoundry/collector/builds/17519638 )
     Send CC job queue length to historians ( Travis Success: https://travis-ci.org/cloudfoundry/collector/builds/17512117 )

Signed-off-by: Kris Kelly <kkelly@pivotallabs.com>