cadfael-bootstrap: new custom command
cadfael-bootstrap: new custom command

Integrate cadfael-installer functionality into cadfaelbrew. The
installer script is easier to use from brew itself as brew can
bootstrap needed packages on supported systems.

SuperNEMO-DBD/cadfaelbrew,SuperNEMO-DBD/cadfaelbrew,SuperNEMO-DBD/cadfaelbrew,SuperNEMO-DBD/cadfaelbrew