Remove redundant printer kit related CSS styles.

These styles became redundant when we suspended sales of the printer kit in [1]

I regenerated `screen.css` using the following command:

    lessc public/stylesheets/screen.less >public/stylesheets/screen.css

This seems to have removed some unrelated and presumably inconsequential
whitespace, presumably due to some difference in version of `lessc`.
I used v1.7.0 of `lessc`.

[1] 78f138e3b336ae108d0b7bd76cd33df2b8bc7a37
Added instructions on how to regenerate CSS files from LESS files
Fix semantics in README.
Remove redundant printer-kit snip.

We've been redirecting [1] the URL for this page for some time, so it's surplus
to requirements.

Although there are still references to the `/printer-kit` path on pages on our
site, these will be redirected to `exciting.io`, so I don't think we need to do
anything about them urgently. At some point it might be nice to add an "Update"
paragraph at the top of relevant blog posts to point out that things have
changed, but I think that can wait for the moment.

[1] https://github.com/freerange/site/blob/master/config/apache/gofreerange.com.conf#L86
Include year in blog post datestamp.

I was talking to @tomstuart about whether I ought to add updates to old blog
posts which have been rendered out-of-date by events. He suggested that
although adding an update would be nice, it's more important to make it clear
when the blog post was written so that it can be read in that context.

I noticed that our blog posts did not include the year in their datestamp and
so I decided to remedy that here.