switched nedb to nedb-promises (#37)

* breaking change: switched to nedb-promises
* Linting
* some dev dependencies
* more tests
* updated package version
* bug fixing
* changed isNaN to isString
* (fix) args[0]

functions/Random.js

@@ -1,14 +1,12 @@
-const Random = { int, use };
-
 function int(min, max) {
     if (!min || !max) {
-        return;
+        return undefined;
     }
     return Math.floor(Math.random() * (Math.floor(max) - Math.ceil(min) + 1)) + min;
 }
 
-function use(str) {
+function use() {
     return true;
 }
-
+const Random = { int, use };
 module.exports = { Random };