fstab.conf: Add a new "crypttabOptions" option that defaults to "luks".
Document that for Debian and Debian-based distributions, the
setting should be changed to "luks,keyscript=/bin/cat".
main.py: Append the options from the above setting to the end of every
line in crypttab.
At least the "luks" option should always be there, because there may be
different encryption types. The Debian initramfs-tools also require the
Debian-specific keyscript option and will otherwise ignore the keyfile
entirely (see pull request #254).
Module descriptors are now module.desc, no configuration allowed inside.
Module config files are <modulename>.conf, installed in
share/calamares/modules.
settings.conf is read from /etc/calamares, then share/calamares, and if
running with --debug also in the current dir.
Module config files are read from /etc/calamares/modules, then
share/calamares/modules, and if running with --debug also in
src/modules/<modulename> relative to the current dir.
