Removed even more cruft from sass/custom/_styles.scss

It is best to keep stuff out of ```sass/custom/_styles.scss```. Everything you write in there overrides all other customizations - including variables which the user may specify under ```sass/custom/_colors.css``` to tweak his colors.
```color: #1863A1;``` on line 77 - for instance - was very bad, as it overrode all custom link colors.

We should try to edit things in the actual theme files rather than in the end-user customization files. To give an example I have migrated the footer section from ```sass/custom/_styles.scss``` (not good) to ```sass/partials/_footer.scss``` (the proper location for footer themeing). It would be great if others could help do this for everything else in ```sass/custom/_styles.scss``` as well.

I have recently written [a post about Octopress themes](http://tutorials.chymera.eu/blog/2013/12/30/octopress-theme/), which has a nice "keep your theme hackable" section at the end - it may be an interesting read for you.