Testing: Switch to use checkmyidp.org

By doing so, it can help me test the provisioning and authentication stages as
well, instead of just simply linting the site. (Which does succeed.)
A quick comment to explain what is going on.
Use better_errors & jazz_hands

Useful things to vastly improve the debugging process. Yay!
We're hosting a copy of an older jquery

Just in case, and it seems that browserid-provider works better that way.
The completed version of the BrowserID monkey patch!
Delete rails stuff I'm not using

...which is about everything that makes Rails unique, except using it as a gem.
Hah!
Remove commented out default, yet unused gems

Also, I like puma, so let's use it. Yay puma!
Cache Github page's index.html as the homepage

It's prettier and actually relevant! Blue and yellow are sort of 'fish like',
too, I guess.