Remove unecessary done callback in tests

Author: posva

tests/vuefire.spec.js

@@ -26,15 +26,14 @@ describe('VueFire', function () {
   })
 
   describe('support Function options', function () {
-    it('option is callable as function', function (done) {
+    it('option is callable as function', function () {
       var spy = sinon.spy()
       expect(function () {
         new Vue({
           firebase: spy
         }).$mount()
       }).to.not.throw()
       expect(spy.calledOnce).to.be.true
-      done()
     })
   })