style: use the max-len solidity rule (#944)

.soliumrc.json

@@ -5,7 +5,7 @@
     "quotes": ["error", "double"],
     "no-empty-blocks": "off",
     "indentation": ["error", 2],
-    "arg-overflow": ["warning", 3],
+    "max-len": ["warning", 79],
     "no-constant": ["error"],
     "security/enforce-explicit-visibility": ["error"],
     "security/no-block-members": ["warning"],