bump cacheddownloader
bump cacheddownloader

[finishes #134886951]

Submodule src/code.cloudfoundry.org/cacheddownloader c95f6997..2c1d1908:
  > fix bookkeeping when a cached file is being used and the expanded dir is closed
  > delete an unused variable
  > rename fileExists -> fileDoesNotExist

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