bump grootfs
bump grootfs

[finishes #153318106]

Submodule src/code.cloudfoundry.org/grootfs 94b76d0..3bd379a:
  > Fix typo in init-store command

Signed-off-by: Julia Nedialkova <7434cf6db6c17ad5b6ef614abe065a9cda1d30c1@hotmail.com>

cloudfoundry-incubator/guardian-release,cloudfoundry-incubator/guardian-release,cloudfoundry-incubator/guardian-release