mock now uses systemd-nspawn by default, but it cannot setup the
/dev/loop* nodes that are needed by lorax and livemedia-creator so users
will need to pass --old-chroot to mock if they are using it.
Run 'make docs' to update the apidocs.
Also moves the README.livemedia-creator and README.product into docs
as ReST documents. They will be installed in /usr/share/doc/lorax/
by the rpm package.
