No bug - Import current AppConstants.
No bug - Import current Fennec strings.
Bug 1097220 - Part 1: extend ClientRecord and add fields to new local client records.
Bug 1097220 - Part 2: extend ClientsDatabase to support new optional fields.
Bug 1097220 - Part 3: extend TestClientsStage to cover new fields.
Bug 1097220 - Part 4: test that optional fields are initialized to null.