Convert tabs to spaces.
_config.yml: re-indent for better readability.
Fix validation errors.
Use the same icons as Bootstrap docs.
Remove default type for script and css.
Add image dimensions.
Add html5shiv and respond.js for older browsers support.
Tweak styles.

* remove border from images
* use `inline-block` for the logo
* remove a couple of duplicate properties
Compress bootstrap-expo.jpg with kraken.io.

Before: 862279 bytes
After:  792647 bytes
Use https for the twitter links.
Make feed.xml valid.

Fixes #12.
Use the variable from _config.yml.
Concatenate the CSS files.
Remove unused classes.
Use the `site.url` variable in more places and avoid repetition.
Exclude README.md from Jekyll's output folder.
Add pygments-manni.css for code highlighting.

Fixes #8.
Highlight json snippet.
Merge pull request #13 from twbs/fixes

Various fixes.