Include Guarantor Accounts in Client Accounts Overview

Include accounts where the client is a guarantor in the client accounts summary api.  This is proposed as part of enhancement for the community app to show accounts where client is a guarantor in the client view (https://github.com/openMF/community-app/issues/1863).

Implementation of this enhancement is covered in pull request 452 (https://github.com/apache/fineract/pull/452/)