add GetFullGroupPowers(agentID, groupID) to groups modules. This returns the 'sum' of powers of all agent roles on that group, apply it to some OSSL (mantis 8777). It May be needed elsewhere

OpenSim/Addons/Groups/Hypergrid/GroupsServiceHGConnector.cs

@@ -268,10 +268,17 @@ namespace OpenSim.Groups
             sendData["METHOD"] = method;
 
             string reply = string.Empty;
-            lock (m_Lock)
-                reply = SynchronousRestFormsRequester.MakeRequest("POST",
+            try
+            {
+                lock (m_Lock)
+                    reply = SynchronousRestFormsRequester.MakeRequest("POST",
                          m_ServerURI + "hg-groups",
                          ServerUtils.BuildQueryString(sendData));
+            }
+            catch
+            {
+                return null;
+            }
 
             //m_log.DebugFormat("[XXX]: reply was {0}", reply);