feat(routing): new DSL and deferred module loading

[pavelgj]

Introduced new routing DSL that allows adding new modules for views.

        views.configure({
          'foo': ngRoute(
              path: '/foo',
              view: 'foo.html',
              enter: (RouteEnterEvent e) => enterFoo(e),
              mount: {
                'bar': ngRoute(
                    path: '/bar',
                    view: 'bar.html',
                    preEnter: (RoutePreEnterEvent e) => checkIfCanEnterBar(e),
                ),
                'baz': ngRoute(
                    path: '/baz',
                    view: 'baz.html',
                    leave: (RouteLeaveEvent e) => checkIfCanLeaveBaz(e),
                )
              }
          ),
          'aux': ngRoute(
              path: '/aux',
              view: 'foo.html',
              defaultRoute: true
          )
        });

Modules can be loaded synchronously

        views.configure({
          'foo': ngRoute(
              path: '/foo',
              modules: () => [
                new Module()..type(NewDirective)
              ],
              view: 'foo.html'
          ),
        });

or asynchronously, for example in case of deferred library loading:

        views.configure({
          'foo': ngRoute(
              path: '/foo',
              modules: () => new Future.value([
                new Module()..type(NewDirective)
              ]),
              view: 'foo.html'
          ),
        });

Fixes #435

[mhevery]

Add missing tests, LGTM otherwise.

[sethladd]

Does this have the viewHtml feature?

[pavelgj]

@sethladd no. How soon do you need it?

[sethladd]

Sorry, just saw the other updates. I'd love it for AngularDart 1.0.