Adds logic for detecting script failures
- HostGroupModel has script failure regex + error flag
- runScriptModel method returns true if detected an error, false otherwise
Merge branch 'master' into ScriptFailureDetection
Merge branch 'ScriptFailureDetection' into CreateLaunchConfig

Conflicts:
	SlingshotCompute/src/main/java/org/slingshot/host/HostGroupModel.java
	SlingshotCompute/src/main/java/org/slingshot/host/HostGroupModelImpl.java