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/src/change_detection/parser/lexer.js

@@ -1,4 +1,4 @@
-import {Injectable} from 'angular2/di';
+import {Injectable} from 'angular2/src/di/annotations_impl';
 import {List, ListWrapper, SetWrapper} from "angular2/src/facade/collection";
 import {int, NumberWrapper, StringJoiner, StringWrapper} from "angular2/src/facade/lang";
 

modules/angular2/src/change_detection/parser/parser.js

@@ -1,4 +1,4 @@
-import {Injectable} from 'angular2/di';
+import {Injectable} from 'angular2/src/di/annotations_impl';
 import {int, isBlank, isPresent,  BaseException, StringWrapper, RegExpWrapper} from 'angular2/src/facade/lang';
 import {ListWrapper, List} from 'angular2/src/facade/collection';
 import {Lexer, EOF, Token, $PERIOD, $COLON, $SEMICOLON, $LBRACKET, $RBRACKET,