Add bootstrap.

I'm using the bootstrap-sass gem since it's now officially part of Bootstrap.
This is generally how you're supposed to use libraries with the asset pipeline:
add a gem which takes care of updating things for you and doing the
integration. I'm not 100% sold on it, exactly, because it relies on people
doing the wrapping rather than importing them directly, but I don't plan on
doing a whole lot of fancy in this app anyway, so it shouldn't be an issue.

The gem instructions don't tell you about adding the file; it took me a bit of
searching to realize that the gem only made the sass files available, rather
than adding bootstrap itself to your project. This makes sense, I guess, if
you want to pick and choose which parts of Bootstrap get used, or to only
use them on part of your sites.
New home page.

Here's a trick that I like in Rails apps: you basically just render the
homepage with `layout: false`, and then shove everything into the single view.

This is an example of where DRY can lead you astray. Yes, I copy and pasted a
bunch of stuff into the view from a layout. Yes, I could, in theory, extract a
common layout and use it for both. No, that would not be worth it. Here's why:

The home page is often just marketing material, and ends up being significantly
different than the rest of the site. Depending on how big your organization is,
it can also end up changing a lot for various reasons, too.

Using the common layout doesn't actually buy you anything, because _the home
page and the rest of your site don't actually have a lot in common_. The
purpose of DRY is to make future change easier. Trying to have this page share
a layout with the rest of the site actually makes future change harder, in my
experience.

Eventually, when I'm ready to launch, this won't be a Bootstrap template, and
will be something real instead.
Bootstrap-ify the layout.

Easy enough. Just the basics.

One thing that's still missing: flash message styling.
Style sign in box
Merge pull request #11 from artisan-tattoo/bootstrap

Bootstrap