Added unit test for the JSON encoder
Added unit test for the JSON encoder


Former-commit-id: f13c089c221cab8dd5bcab9aeeb36892fb24f7db [formerly 172528b6ab8f80bcf9626e464270f47bebe0d092]
Former-commit-id: 3dcb1fd029c2695f2928297584fa7efee21700f2
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine