Add default values for new params
Add env blacklist/whitelist to hgfs

Also simplify how per-repo configuration params are handled, putting
them in a dictionary like was recently done for gitfs.
Consistency/cleanup changes for gitfs
Restrict listing files/dirs that aren't exposed

This keeps files/dirs which aren't exposed due to the
whitelist/blacklist from being listed in cp.list_master and
cp.list_master_dirs. It also fixes envs() to not include these
environments.
Restrict listing files/dirs that aren't exposed

This keeps files/dirs which aren't exposed due to the
whitelist/blacklist from being listed in cp.list_master and
cp.list_master_dirs.