bump lager
bump lager

[finishes #150142140]

Submodule src/code.cloudfoundry.org/lager 77a306a1..0bfa98e4:
  > Remove failing and outdated benchmark tests
  > Fix code which breaks compiler in match_log_entry_test

Signed-off-by: Caroline Taymor <6220814f63f705589fa0394c3218bcae0c084690@pivotal.io>

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