ScheduledJobPoller: only load each request once, avoids IllegalArgumentException in Maps.uniqueIndex
Merge pull request #356 from stevenschlansker/fix-poller-iae

ScheduledJobPoller: only load each request once, avoids IllegalArgumentException in Maps.uniqueIndex
Expose SingularityTaskId to the executor through environment variables
De-crapify setting of environment variables
Take Object for value and toString it for convenience