Router should notify url property change on navigate events

This fixes an issue where observers on the router.url property (used by LinkTo) are not updated if the user clicks the back or forward buttons.
Don't blow-away view template if fails to lookup template
Check for user specified templateName on View before setting our own
Remove assert so that we don't break existing tests
Added a test to ensure template is not blown away when setting up a view with user specified templateName
Merge pull request #1756 from ivanvanderbyl/bug/setupViews-should-not-blow-away-template

Fixed setupView to avoid blowing away view template if router fails to lookup a template
Merge pull request #1764 from ivanvanderbyl/bug/should-trigger-url-property-change

Router should notify url property change on navigate events
Add `action` support to Ember.TextField
Change the API to this.resource/this.route

This will hopefully be the last API change.
Website docs forthcoming.
Fix failing router tests using old API
Set up Route.currentModel when entering w/ transitionTo

Test via @lcoq