GUACAMOLE-723: Move getClientIdentifier() to GroupListItem for convenience of other uses of the guacGroupList directive.

guacamole/src/main/webapp/app/home/templates/home.html

@@ -23,7 +23,6 @@
         </div>
         <div class="all-connections">
             <guac-group-list
-                context="context"
                 connection-groups="filteredRootConnectionGroups"
                 templates="{
                     'connection'       : 'app/home/templates/connection.html',