Cleanup procs

Maintain a flatfile containing the process identifiers of all active activity servers. Ensure that any "zombie" processes are killed whenever starting the top-level server. (This solution originally described in gh-118.)

@mzgoddard Mind taking a look at this?
Heh. One of your tests also uses `.always(done)`. I'm not tied to any one method, but I'll comment the ones that need one of the methods.