restapi: Fix group search and add

The RESTAPI doesn't currently accept group names with the format
domain/organization/group. This patch fixes that.

Change-Id: Iffb4ba829d5e07b46c0bb6d71e46bdbdbcb2442c
Bug-Url: https://bugzilla.redhat.com/1057214
Signed-off-by: Juan Hernandez <juan.hernandez@redhat.com>