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/angular2/src/core/application_tokens.ts

@@ -1,5 +1,5 @@
 import {OpaqueToken, Provider} from 'angular2/src/core/di';
-import {CONST_EXPR, Math, StringWrapper} from 'angular2/src/core/facade/lang';
+import {CONST_EXPR, Math, StringWrapper} from 'angular2/src/facade/lang';
 
 /**
  *  @internal