Rename Commit#revision to Commit#sha for git

Since we are only supporting git right now, stick to semantics and give
the column a git-specific name for a revision: sha.
Wall display is the root path
Add tmux dashboard for development

Since we have several things that are running in the background with
Guard, Zeus, and LiveReload, run `bin/devboard` to get things going for
quick development.

[ci skip]