Make bundling for deployment happy

When deploying to heroku or running on travis, I was seeing:

You are trying to install in deployment mode after changing
       your Gemfile. Run `bundle install` elsewhere and add the
       updated Gemfile.lock to version control.
       You have added to the Gemfile:
       * therubyracer (~> 0.11.3)

I assume because of the conditional we had for platform. Sooo let's take
that out.
What is this i don't even...

Somehow the polyglot lines got duplicated a whole bunch in the
Gemfile.lock????
Add a deploy to heroku button
Merge pull request #813 from carols10cents/heroku-button

Adds Heroku button for two-click, free deployment.

It's magic, as far as I can tell, but good magic. The kind that also makes unicorns possible and lets you walk on rainbows.