Augment 'git to take optional ok-statuses set.

This allows us to avoid throwing an exception for statuses the caller
expects.
Also have 'parse-tag normalize the :proj name.
Fix 'newest-voom-ver-by-spec to handle top-level project.

The previous constraint by path is insufficient when the project is a
top-level project. The path is empty and will match all refs printed
instead of voom-tags. We now match by project name as well.
Implement bottom half of box-add functionallity; finding projects.

Project name will match as subtring of all available projects across
all repos and all repo path locations. If the matching set across all
of these is more than one match, print an error.