Add compact repo list printing

[rfbgo]

The existing format is great but gets very long:

==> 4 applications repositories.
builtin.mock    /Users/robertbird/ramble/injconf/var/ramble/repos/builtin.mock
extra       /Users/robertbird/extra
builtin         /Users/robertbird/ramble/var/ramble/repos/builtin
==> 4 modifiers repositories.
builtin.mock    /Users/robertbird/ramble/injconf/var/ramble/repos/builtin.mock
builtin         /Users/robertbird/ramble/var/ramble/repos/builtin
==> 3 package_managers repositories.
extra      /Users/robertbird/extra
builtin        /Users/robertbird/ramble/var/ramble/repos/builtin
==> 3 workflow_managers repositories.
extra      /Users/robertbird/extra
builtin        /Users/robertbird/ramble/var/ramble/repos/builtin
==> 3 systems repositories.
...

This offers a compact alternative:

 $ ramble repo list -c
==> 4 repositories.
NAMESPACE     TYPES                    PATH
builtin       all                      /Users/robertbird/ramble/var/ramble/repos/builtin
builtin.mock  applications, modifiers  /Users/robertbird/ramble/injconf/var/ramble/repos/builtin.mock
extra     all (non-utility)        /Users/robertbird/extra