WL-3615 : Roster tool doesn't seem to like our sections

Code throwing IdNotFoundException when trying to find a section in coursemanagement which it might not have.
Surrounding it with empty try catch in roster2 to catch this case.
WL-3615 : try catch for another method in RosterSiteEntityProvider

private List<RosterEnrollment> getEnrollmentSets(String siteId,
			GroupProvider groupProvider)
also throws an exception
Merge pull request #1 from ox-it/WL-3615

WL-3615 : Roster tool doesn't seem to like our sections