Add directionaltiy reexport

Author: jelbourn

src/cdk/bidi/index.ts

@@ -11,6 +11,7 @@ import {DOCUMENT} from '@angular/platform-browser';
 import {Dir} from './dir';
 import {DIR_DOCUMENT, Directionality, DIRECTIONALITY_PROVIDER} from './directionality';
 
+export * from './directionality';
 
 export {
   Directionality,