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/angular2/test/core/application_spec.js

@@ -16,7 +16,8 @@ import {Component, Directive} from 'angular2/src/core/annotations_impl/annotatio
 import {DOM} from 'angular2/src/dom/dom_adapter';
 import {ListWrapper} from 'angular2/src/facade/collection';
 import {PromiseWrapper} from 'angular2/src/facade/async';
-import {bind, Inject} from 'angular2/di';
+import {bind} from 'angular2/di';
+import {Inject} from 'angular2/src/di/annotations_impl';
 import {View} from 'angular2/src/core/annotations_impl/view';
 import {LifeCycle} from 'angular2/src/core/life_cycle/life_cycle';
 import {Testability, TestabilityRegistry} from 'angular2/src/core/testability/testability';

modules/angular2/test/core/compiler/element_injector_spec.js

@@ -6,7 +6,8 @@ import {ProtoElementInjector, PreBuiltObjects, DirectiveBinding, TreeNode}
 import {Parent, Ancestor} from 'angular2/src/core/annotations_impl/visibility';
 import {Attribute, Query} from 'angular2/src/core/annotations_impl/di';
 import {Directive, onDestroy} from 'angular2/src/core/annotations_impl/annotations';
-import {Optional, Injector, Inject, bind} from 'angular2/di';
+import {bind, Injector} from 'angular2/di';
+import {Optional, Inject} from 'angular2/src/di/annotations_impl';
 import {AppProtoView, AppView} from 'angular2/src/core/compiler/view';
 import {ViewContainerRef} from 'angular2/src/core/compiler/view_container_ref';
 import {ProtoViewRef} from 'angular2/src/core/compiler/view_ref';