Make code in Rakefile OO

Add ImageBuilder and DiskBuilder classes to perform the heavy
lifting of creating a system image and a disk. The rake tasks
simply use these objects.
Add a build dir to flightdeck (sub)project

Which will be the output dir of the flightdeck build (where we
drop off the tarball)
Add a .gitignore to the hangar dir.

So we can ignore the image file.
Discard editor-backup file.

An old ~ file had made its way into the vcs. Delete it.
Add a Authenticator middleware (rack)

To allows us to do http (basic) authentication. This is a specialized
derivative of Rack::Auth which will conditionally skip auth on certain
specified ports.