feat(keyEvents): support for <div (keyup.enter)="callback()">

This commit adds a plugin for the event manager, to allow a key name to
be appended to the event name (for keyup and keydown events), so that
the callback is only called for that key.

Here are some examples:
 (keydown.shift.enter)
 (keyup.space)
 (keydown.control.shift.a)
 (keyup.f1)

Key names mostly follow the DOM Level 3 event key values:
http://www.w3.org/TR/DOM-Level-3-Events-key/#key-value-tables

There are some limitations to be worked on (cf details
in https://github.com/angular/angular/pull/1136) but for now, this
implementation is reliable for the following keys (by "reliable" I mean
compatible with Chrome and Firefox and not depending on the keyboard
layout):
- alt, control, shift, meta (those keys can be combined with other keys)
- tab, enter, backspace, pause, scrolllock, capslock, numlock
- insert, delete, home, end, pageup, pagedown
- arrowup, arrowdown, arrowleft, arrowright
- latin letters (a-z), function keys (f1-f12)
- numbers on the numeric keypad (but those keys are not correctly simulated
by Chromedriver)

There is a sample to play with in examples/src/key_events/.

close #523
close #1136

modules/angular2/src/core/application.js

@@ -18,6 +18,7 @@ import {EmulatedUnscopedShadowDomStrategy} from 'angular2/src/render/dom/shadow_
 import {XHR} from 'angular2/src/services/xhr';
 import {XHRImpl} from 'angular2/src/services/xhr_impl';
 import {EventManager, DomEventsPlugin} from 'angular2/src/render/dom/events/event_manager';
+import {KeyEventsPlugin} from 'angular2/src/render/dom/events/key_events';
 import {HammerGesturesPlugin} from 'angular2/src/render/dom/events/hammer_gestures';
 import {Binding} from 'angular2/src/di/binding';
 import {ComponentUrlMapper} from 'angular2/src/core/compiler/component_url_mapper';
@@ -81,7 +82,7 @@ function _injectorBindings(appComponentType): List<Binding> {
           [appComponentRefToken]),
       bind(LifeCycle).toFactory((exceptionHandler) => new LifeCycle(exceptionHandler, null, assertionsEnabled()),[ExceptionHandler]),
       bind(EventManager).toFactory((zone) => {
-        var plugins = [new HammerGesturesPlugin(), new DomEventsPlugin()];
+        var plugins = [new HammerGesturesPlugin(), new KeyEventsPlugin(), new DomEventsPlugin()];
         return new EventManager(plugins, zone);
       }, [VmTurnZone]),
       bind(ShadowDomStrategy).toFactory(