fix(animations): change trigger binding syntax to function as a property binding []

Animation triggers can now be set via template bindings `[]`

BREAKING CHANGE:

animation trigger expressions within the template that are assigned as
an element attribute (e.g. `@prop`) are deprecated. Please use the
Angular2 property binding syntax (e.g. `[@prop]`) when assigning
properties.

```ts
// this is now deprecated
<div @trigger="expression"></div>

// do this instead
<div [@trigger]="expression"></div>
```

modules/playground/src/animate/app/animate-app.ts

@@ -22,7 +22,7 @@ import {
   selector: 'animate-app',
   styleUrls: ['css/animate-app.css'],
   template: `
-    <div @backgroundAnimation="bgStatus">
+    <div [@backgroundAnimation]="bgStatus">
       <button (click)="state='start'">Start State</button>
       <button (click)="state='active'">Active State</button>
       |
@@ -30,7 +30,7 @@ import {
       <button (click)="state='default'">Unhandled (default) State</button>
       <button style="float:right" (click)="bgStatus='blur'">Blur Page</button>
       <hr />
-      <div *ngFor="let item of items" class="box" @boxAnimation="state">
+      <div *ngFor="let item of items" class="box" [@boxAnimation]="state">
         {{ item }}
       </div>
     </div>