Remove Mercurius from release JSON, Sadly it's dead we may address it at a later date.

jsons/1.12-rel.json

@@ -140,18 +140,5 @@
       "serverreq":true
     }
   ]
-},
-"optionals": [
-    {
-        "name": "Mercurius",
-        "client": true,
-        "server": true,
-        "default": true,
-        "inject": true,
-        "desc": "A mod that collects statistics about Minecraft and your system.<br>Useful for Forge to understand how Minecraft/Forge are used.",
-        "url": "http://www.minecraftforge.net/forum/index.php?topic=43278.0",
-        "artifact": "net.minecraftforge:MercuriusUpdater:1.12",
-        "maven": "http://files.minecraftforge.net/maven/"
-    }
-]
+}
 }