chore(pipe): implement PipeTransform interface

Close #144

Author: EmmanuelDemey

addon/ng2/blueprints/pipe/files/src/app/pipes/__name__/__name__.ts

@@ -1,10 +1,10 @@
-import {Pipe} from 'angular2/core';
+import {Pipe, PipeTransform} from 'angular2/core';
 
 
 @Pipe({
   name: '<%= classifiedModuleName %>'
 })
-export class <%= classifiedModuleName %> {
+export class <%= classifiedModuleName %> implements PipeTransform {
 
   transform(value, args?) {
     return null;