Add styling for blockquotes

[mattlangan]

There are 2 use cases for the <blockquote> and <pre> tags:

1. Displaying code snippets (either inline or as a block)
2. Quoting text

Here are examples of how GitHub-flavored kramdown handles them:

Inline code snippet:
Run $ bundle install to add your gems

Block-level code snippet:

$ git checkout master
$ git pull
$ git checkout -b my-feature

Quoting text:

It's not a question of where he grips it! It's a simple question of weight ratios! A five ounce bird could not carry a one pound coconut.