GRP-10: Automate a group's configuration

Executive Summary: 
An application developer or system administrator (hereafter referred to as the “group user”) needs to enable an application (or science gateway) to access and/or manage community groups. In other words, we need APIs for use cases GRP-02, -03, -05, and -06 in addition to a human interface.
User Importance Summary: 
Community members need to be able to define arbitrary groups of people to which they can refer for authorization and communication purposes. The ability to access and manage these groups via APIs, SDKs, and CLIs is vital to enabling their use in applications.
Target Communities and Sizes: 
Service providers - 100 < N < 1,000 Campus IT administrators integrating systems with XSEDE - 10 < N < 100 Science gateway and application developers - 100 < N < 1,000