Bump src/collector

Bump cloudfoundry/collector:
  Alex Suraci and Maria Shaldibina:
     group varz endpoints by IP rather than index ( Travis created: https://travis-ci.org/cloudfoundry/collector/builds/10984305 )
     cloud controller: report ip as a tag ( Travis Failed: https://travis-ci.org/cloudfoundry/collector/builds/10952798 )