feat(decorators): adds decorator versions of DI annotations.

In 'angular2/di' the symbol:
- Inject is a decorator
- InjectAnnotation is an annotation

Internally one an get a hold of annotations without *Annotations appened
(to make ts2dart work without workarounds) by importing from
'angular2/src/di/annotations_impl' instead of 'angular2/di'. This is
needed only for users that transpile through TS and through ts2dart.

modules/benchmarks/src/largetable/largetable_benchmark.js

@@ -18,7 +18,8 @@ import {BrowserDomAdapter} from 'angular2/src/dom/browser_adapter';
 
 import {ListWrapper} from 'angular2/src/facade/collection';
 
-import {Inject, bind} from 'angular2/di';
+import {bind} from 'angular2/di';
+import {Inject} from 'angular2/src/di/annotations_impl';
 
 export const BENCHMARK_TYPE = 'LargetableComponent.benchmarkType';
 export const LARGETABLE_ROWS = 'LargetableComponent.rows';