Add first_to_solve to scoreboard JSON schema.

Author: nickygerritsen

contest-api/json-schema/scoreboard.json

@@ -50,7 +50,8 @@
 									"minimum": 0
 								},
 								"solved": { "type": "boolean" },
-								"time": { "type": "integer", "minimum": 0 }
+								"time": { "type": "integer", "minimum": 0 },
+								"first_to_solve": { "type": "boolean" }
 							},
 							"oneOf": [
 								{