mktmpio: Temporary databases that start instantly.

Thanks for posting, @glougheed! I've added a coupon code for people visiting the site from here (20% off, forever). I created mktmpio because I was tired of being jealous of people using Travis and other hosted CI services who get databases as part of their build environments. I need to test on a bunch of platforms, not just whatever flavour of Linux they run. Having no luck finding something like a `mktemp` command for databases, I gave up the search and just made one! Turns out that in addition to running tests against temporary database servers, I've also found it really useful for getting a simple DB shell whenever I want to show someone something without installing anything. I'd love to get some feedback, suggestions, complaints (or, *gasp*, signups).