ACE-1790: Don't throw an exception when no group data for the current user can be returned. Instead just set an empty string. This addresses the issue of the user dashboard failing to load after activating an account on the Cloud. The group membership data is only required for checking for additional memberships in for role based UI rendering. On Cloud the user will never be a member of any additional groups on account activation so this is not an issue.

git-svn-id: https://svn.alfresco.com/repos/alfresco-open-mirror/alfresco/HEAD/root@71816 7033f55c-6c29-4ad8-afba-765cb616e738