Singularity-0.4.1

Updated in 0.4.1:

• #351 - Update Mesos to 0.21.0 and add option for pure java API code.
• #346 - Factor out the Scheduler lock.
• #355 - Expose SingularityTaskId to the executor through environment variables
• #365 - Run the History persister only on the leading server.
• #366 - Remove @Nonnull from primitive fields
• #373 - Add support for Docker 'privileged' option to DockerInfo
• #372, #396 - Warning Patrol
• #379 - hide icon for run-now when daemon task
• #382 - add indicator for overdue tasks
• #387 - update dev doc to match reality
• #386 - Fix executor cleanup
• #369 - move webhook processing to leader only
• #378 - Update to basepom-8
• #397 - Remove bad dependency, make build pass again.
• #360 - Change MesosResourcesObject to be resource agnostic.
• #403 - Remove superflous c'tor inject.
• #402 - Ignore autogenerated PMD ruleset files (Eclipse PMD plugin does this)

Also, we released singularity-logfetch, a tool for grepping and tailing singularity task logs: https://github.com/HubSpot/Singularity/tree/Singularity-0.4.1/scripts