Keep tests in json format

So the results are typed

tests_dir/people_join_rooms.result

@@ -1,13 +1 @@
-id,name,chief,age,room,phone
-0,jack,0,22,1,1516
-1,carl,0,20,4,1041
-2,john,1,30,2,1617
-3,dean,1,33,2,1617
-4,eve,0,25,5,9212
-5,duncan,4,30,1,1516
-6,paul,4,30,5,9212
-7,alia,1,28,1,1516
----,---,---,---,"0","1515"
----,---,---,---,"3","1601"
----,---,---,---,"6","1424"
----,---,---,---,"7","1294"
+{"content": [[0, "jack", 0, 22, 1, 1516], [null, null, null, null, 6, 1424], [null, null, null, null, 3, 1601], [7, "alia", 1, 28, 1, 1516], [2, "john", 1, 30, 2, 1617], [3, "dean", 1, 33, 2, 1617], [5, "duncan", 4, 30, 1, 1516], [4, "eve", 0, 25, 5, 9212], [1, "carl", 0, 20, 4, 1041], [null, null, null, null, 0, 1515], [null, null, null, null, 7, 1294], [6, "paul", 4, 30, 5, 9212]], "header": ["id", "name", "chief", "age", "room", "phone"]}