Update passphrase entropy page and fix Sass issue

Two unrelated commits, sorry:

- Update passphrase recommendation as discussed.
- Move all the breadcrumb Sass into the breadcrumb file. I rejigged the padding at the same time to fix the colour bar on the search page.

![screen shot 2014-02-11 at 22 18 13](https://f.cloud.github.com/assets/121219/2142855/81145ffa-936a-11e3-99e6-aaa6561e3868.png)