GRP-12: Use groups to control access within an XSEDE L1 or L2 resource

Executive Summary: 
An L1 or L2 service provider needs to use groups to control access to his/her resource. The most common reason is to limit access to the resource to project groups that have active allocations via an official allocation process.
User Importance Summary: 
XSEDE community members need to be able to define arbitrary groups of people to which they can refer throughout the XSEDE system for authorization and communication purposes. Allocated researchers and L1/L2 service providers (SPs) need to be able to use these groups on L1/L2 resources.
Target Communities and Sizes: 
XSEDE SP administrators - 10 < N < 100