Improve responsiveness

Improves the responsiveness throughout the application, specifically:

- Adjust directory so columns line up on small screens.
- Adjust cookbook header so follow button doesn't fall off.
- Ensure cookbook sidebar has padding at the top.
- Improve look, feel and responsiveness of welcome view.
- Add wrapper class for welcome page.
- Adjust edit cookbook look so there aren't so many buttons flying around.
- Adjust font size for better readability on smaller displays.
- Fix some minor display bugs that appear on smaller displays.

Clean up stylesheets to try to adhere to code style guide.
Merge pull request #395 from opscode/responsiveness

Improve responsiveness throughout application