Remove outdated post on bound handlebars helpers

Ember now has Ember.Handlebars.helper
(http://emberjs.com/guides/templates/writing-helpers/), but [this post](http://techblog.fundinggates.com/blog/2012/08/ember-handlebars-helpers-bound-and-unbound/)
still is top-ranked on Google for "bound handlebars helpers", spreading
outdated information.

@kategengler, do you think we can just remove this? I don't think it can be salvaged.