Merge pull request #1 from HubSpot/master

Merge
Unlock the possibility to launch a scheduled request on multiple
instances (distributed scheduled tasks)
Use Quartz cron syntax instead of Cron to Quartz Cron conversion
Remove unused static Joiner, organize imports
Feature: requests can now be run on a specific rack
Fix: nullpointer exception when the scheduled task is designed to run
only once at a given date
Merge pull request #2 from HubSpot/master

pull from HubSpot
integrate changes
Merge branch 'master' of github.com:HubSpot/Singularity

Conflicts:
	SingularityBase/src/main/java/com/hubspot/singularity/SingularityRequest.java
	SingularityBase/src/main/java/com/hubspot/singularity/SingularityRequestBuilder.java
	SingularityService/src/main/java/com/hubspot/singularity/data/SingularityValidator.java
	SingularityService/src/main/java/com/hubspot/singularity/mesos/SingularityRackManager.java
	SingularityService/src/main/java/com/hubspot/singularity/scheduler/SingularityScheduler.java
remove local conf