domtool-addcert: use domtool-config, support non-afs cert/key dirs

domtool-addcert: use domtool-config, support non-afs cert/key dirs

Removed `chown -R domtool.nogroup' calls since they are meaningless in
afs and incorrect on normal file systems. chown -R the key dir to the
user.nogroup unless `-unsafe' is passed, which allows the creation of
useless keys (the user running the script can read the key instead of
the intended user, which is ok for development).

Still needs improvement.