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/http/static_request.ts

@@ -8,7 +8,7 @@ import {
   isPresent,
   isJsObject,
   StringWrapper
-} from 'angular2/src/core/facade/lang';
+} from 'angular2/src/facade/lang';
 
 // TODO(jeffbcross): properly implement body accessors
 /**