chore: upgrade lint configuration

package.json

@@ -35,8 +35,8 @@
     "timers-ext": "^0.1.2"
   },
   "devDependencies": {
-    "eslint": "^4.6.1",
-    "eslint-config-medikoo-es5": "^1.4.3",
+    "eslint": "^5.3",
+    "eslint-config-medikoo-es5": "^1.6",
     "plain-promise": "^0.1.1",
     "tad": "^0.2.7"
   },
@@ -46,6 +46,9 @@
     "globals": {
       "setTimeout": true,
       "clearTimeout": true
+    },
+    "rules": {
+      "max-lines-per-function": "off"
     }
   },
   "scripts": {