Update blog example with up-to-date libraries

Updated Libraries:
Ember 1.5.0 => 1.7.0
emberFire => latest
Handlebars 1.2.1 => 1.3.0
Firebase => 1.1.0

Changes:
Replace `findAll` with `find`
I'm getting the Handlebars error "Cannot read property 'slice' of undefined" when I load some of the individual posts. Know why this might be happening? Otherwise the update looks good to me!