Second (and hopefully last?) set of RC images for 18.04.1

[Adam Conrad]

Following up on jibel's call for testing yesterday, I tackled every new
bug people reported, and a couple that I just noticed in passing, and
turned off -proposed to build a proper RC image set.

These should have the serial 20180725 for all but Budgie, which had a
second build today and is 20180725.1 (I decided to remove some cruft
that was only going to grow with each point release).

Please, please, please test these.  Get your friends to test.  Teach
your cat how to operate a USB stick.  Images that have no testing can't
be released.

... Adam