Remove obsolete description from README.md
Remove obsolete description from README.md

handlebars filter is removed at 50d3eef40.
Asset compilation supersede this filter.

maschwenk/ember-rails,tricknotes/ember-rails,ipmobiletech/ember-rails,maschwenk/ember-rails,bcavileer/ember-rails,tricknotes/ember-rails,emberjs/ember-rails,maschwenk/ember-rails,tricknotes/ember-rails,bterkuile/ember-rails,bcavileer/ember-rails,ipmobiletech/ember-rails,bterkuile/ember-rails,emberjs/ember-rails,bcavileer/ember-rails,emberjs/ember-rails,bterkuile/ember-rails,ipmobiletech/ember-rails