Add Handlebars 2.0 update blog post.

Needs to be held for the updates and packages to be published as described (hopefully soon), but I wanted to get this out for review and to start letting folks know what is happening....
Honestly, the only thing I know about is the fact that components can be properly nested in subfolders (which is pretty huge for me).  I'll just link to the release notes from Handlebars.