remove the digest command and cli

These were originally thought to be needed but the middleware has
proved to work so well that these features haven't been very useful
so far.  Also, as new features were added, these "manual digest"
features weren't updated so they kinda fell by the wayside.

I am removing both the CLI and the manual digest cmd and all related
handling.  I would like to see the file, combination, and compilation
features mature and then maybe revisit these at a later date.

Closes #48.
Closes #49.
Merge pull request #56 from redding/kr-rm-digestcmd

remove the digest command and cli