Apparently systemd/udev no longer create units for tty* devices; without
those units anaconda-shell@.service wouldn't start.

Add a systemd-generator script that puts anaconda on the correct console
tty, then puts shells on tty2 and the first virtualization console
(unless we're using it for anaconda).

Adding "TTYPath" to the systemd services means systemd takes care of
setting up all the terminal stuff - picking the right TERM value,
setting the keyboard mode to K_UNICODE, and all that esoteric weirdness.

Also, move anaconda's dependencies into anaconda.target, and make
anaconda start *after* anaconda.target, just so we can be sure that e.g.
NetworkManager is active before anaconda starts.

(as a bonus, it also shuts off plymouth correctly, just in case we ever
want to have a anaconda-specific bootsplash)

following getty@.service, make sure we run the shell after plymouth
quits, etc.