fix(icon): export icon registry as part of icon

Author: kara

src/components/icon/icon.ts

@@ -14,7 +14,7 @@ import {NgClass} from 'angular2/common';
 import {BaseException} from 'angular2/src/facade/exceptions';
 
 import {MdIconRegistry} from './icon-registry';
-
+export {MdIconRegistry} from './icon-registry';
 
 /** Exception thrown when an invalid icon name is passed to an md-icon component. */
 export class MdIconInvalidNameException extends BaseException {

src/demo-app/icon/icon-demo.ts

@@ -1,6 +1,5 @@
 import {Component, ViewEncapsulation} from 'angular2/core';
-import {MdIcon} from '../../components/icon/icon';
-import {MdIconRegistry} from '../../components/icon/icon-registry';
+import {MdIcon, MdIconRegistry} from '../../components/icon/icon';
 
 @Component({
   selector: 'md-icon-demo',