Use scss for css.

This lets rails pre-process the CSS so that it can include the right
links in production.
Use rails helpers to find urls.

In production images are moved around to make it easier to deploy
new versions of images, so that no-one downloads the old version by
mistake. image-url() will find the correct url for us.
merge
fixed css locally
fixed header
Fit text on home page, changed all methods pages