Automated droplet init/cleanup

[rostwald]

Discussion about automated droplet cleanup and initialization

Originally posted by @morganwdavis in https://github.com/morganwdavis/freebsd-digitalocean/issues/3#issuecomment-486145800

As for the cleanup script and which DO base images to support, I suppose the latest is fine as that's all I'd ever need it for. I hope there are no requirements from others that would need to install an older base version.

So we agree on prioritising 11.x images.

I'll do my initial porting and testing on the latest image available (11.2) and work my way backwards. I haven't yet looked at the 10.x images (and it has been quite some time since I spun up a 10.x droplet), but I hope DO didn't use a completely different configuration on those so we can use the same routines on them.

[morganwdavis]

Lost in the updated README was a list of extraneous files and directories that appeared in the DO 10.x images. Will need to review the earlier versions to reincorporate them. As long as we're doing quiet removals of stuff that may not exist (which is fine) it should keep the error output down.