Split base box from dev box.

This is just a copy-paste, at the moment.
Rewrite tutorial config.
Share cleaup script.
Require setuptools, since we use entrypoints.
Unpin zope.interface version.

fedora has pushed an updated, and setuptools complains.
We don't need symlinks, just relative paths.
Accept the version we used to require of setuptools.
Download zfs keys (i.e. zfs-release package) over https.
Use s3 URL for zfs-release package.

There is no good way to securly delegate HTTPs URLs.
Script for building boxes.
Update documentation.
Remove caching that is only relevant to examples.
Merge branch 'split-base-box' of github.com:ClusterHQ/flocker into split-base-box
Fix markup.
Fix spelling issues and explain a bit more.
Fix symlinks.
Pass correct argument to function.
Ignore Vagrant boxes we've built.
Notice non-0 exit code.
Specify a specific image version for the tutorial.