Remove async dependency in favor of promises

It appears that `async` is relied upon for just two calls to `async.series()`. Here's my attempt at replicating this behavior using a promise chain. There's still one failing test case that I can't get to pass so I'm hoping someone more familiar with the internals can take a look:

```
PhantomJS 1.9.7 (Mac OS X) ActiveResource Querying base#where utilizes findURL by default has associated method #all that returns all instances FAILED
	Error: Unexpected request: GET http://api.faculty.com/grid-controllers?system_id=8
	No more request expected
	    at $httpBackend (/Users/marshall/Projects/ngActiveResource/bower_components/angular-mocks/angular-mocks.js:1179)
	    at sendReq (/Users/marshall/Projects/ngActiveResource/bower_components/angular/angular.js:8181)
	    at /Users/marshall/Projects/ngActiveResource/bower_components/angular/angular.js:7921
	    at /Users/marshall/Projects/ngActiveResource/bower_components/angular/angular.js:11319
	    at /Users/marshall/Projects/ngActiveResource/bower_components/angular/angular.js:11319
	    at /Users/marshall/Projects/ngActiveResource/bower_components/angular/angular.js:11405
	    at /Users/marshall/Projects/ngActiveResource/bower_components/angular/angular.js:12412
	    at /Users/marshall/Projects/ngActiveResource/bower_components/angular/angular.js:12224
	    at /Users/marshall/Projects/ngActiveResource/bower_components/angular/angular.js:12516
	    at done (/Users/marshall/Projects/ngActiveResource/bower_components/angular/angular.js:8204)
	    at handleResponse (/Users/marshall/Projects/ngActiveResource/bower_components/angular-mocks/angular-mocks.js:1131)
	    at /Users/marshall/Projects/ngActiveResource/bower_components/angular-mocks/angular-mocks.js:1448
	    at /Users/marshall/Projects/ngActiveResource/spec/angular-resource/active-resource.spec.js:1332
PhantomJS 1.9.7 (Mac OS X): Executed 329 of 329 (1 FAILED) (2.087 secs / 1.957 secs)
```