Adds liniting into the workflow (#3082)

* initial linting of src

* fix indent to 2 spaces

* Removes unnecessary rules

* ignore spec folder for now

* Spec linting

* Fix spec indent

* nits

* nits

* no no-empty rule

spec/InMemoryCacheAdapter.spec.js

@@ -5,7 +5,7 @@ describe('InMemoryCacheAdapter', function() {
   var VALUE = 'world';
 
   function wait(sleep) {
-    return new Promise(function(resolve, reject) {
+    return new Promise(function(resolve) {
       setTimeout(resolve, sleep);
     })
   }
@@ -15,8 +15,6 @@ describe('InMemoryCacheAdapter', function() {
       ttl: NaN
     });
 
-    var noop = () => {};
-
     // Verify all methods return promises.
     Promise.all([
       cache.put(KEY, VALUE),