Bug 1018707 - Empty CustomCSS

Copied CustomCSS into this file so it is minified. Myself and @groovecoder have "subscribed" to changes to CustomCSS and when changes to the file occur they can be moved into a proper place in the code base. We can work through this file slowly integrating its contents into our code base but in the mean time at least it's minified.

When this goes into staging the contents of CustomCSS need to be emptied for testing.

When this goes into production the contents of CustomCSS will need to be removed there as well.
We usually do imports at the tops of files. Does <i>wiki-customcss</i> need to be imported after everything else?

If so, I think it would be best for consistency if we used the same approach we use in <a href="https://github.com/mozilla/kuma/blob/master/media/redesign/stylus/main.styl"><i>main.styl</i></a>&mdash;that is, have a <i>wiki.styl</i> file that imports files in the necessary order from a directory called <i>wiki</i>.