* Change build_*_env jobs to pull base image of current "tag"
instead of "master" image
* Change nightly flow so build_*_env jobs now gated by build_base (so
change in previous bullet works in nightly)
* Bugfix in CheckpointDataStore: Call to object.__init__ with
parameters
* Disabling unstable Doom A3C and ACER golden tests
* GraphManager.set_session also sets self.sess
* make sure that GraphManager.fetch_from_worker uses training phase
* remove unnecessary phase setting in training worker
* reorganize rollout worker
* provide default name to GlobalVariableSaver.__init__ since it isn't really used anyway
* allow dividing TrainingSteps and EnvironmentSteps
* add timestamps to the log
* added redis data store
* conflict merge fix
Gal Novik