refactor(core): move facades out of core

This is part of ongoing work to make core platform-independent.

BREAKING CHANGE

All private exports from 'angular2/src/core/facade/{lang,collection,exception_handler}' should be replaced with 'angular2/src/facade/{lang,collection,exception_handler}'.

modules/benchpress/src/common_options.ts

@@ -1,5 +1,5 @@
 import {bind, provide, Provider, OpaqueToken} from 'angular2/src/core/di';
-import {DateWrapper} from 'angular2/src/core/facade/lang';
+import {DateWrapper} from 'angular2/src/facade/lang';
 
 export class Options {
   static get DEFAULT_PROVIDERS(): Provider[] { return _DEFAULT_PROVIDERS; }