Delete GL Groups and change project namespacing

This push is meant to #11 (closed) and #5 (closed), by refining the Project model so that it no longer references the GLGroup model, deleting all references to GLGroups, deleting the GlGroup model, and deleting the project.short_name_with_namespace attribute. It updates the save definitions of projects to no longer ask the API for a group.

Additionally, project templates that referred to either project.group or project.short_name_with_namespace have been updated so that project.name_with_namespace is used instead, which is consistent with the API.