1) This didn't do anything useful prior to rsyslog, as sysklogd would reset it.
2) This overrides the kernel commandline, for people who want to temporarily reset it there
3) This actually turns messages back on out from underneath plymouth, which isn't nice.

To frob the console loglevel, pass it on the kernel command line.

It cannot work reliably as done in this way. (It's possible to do
surgery to do it in plymouth itself, but not here.)

Interactive startup via the 'confirm' commandline option is still
available.

If upstart directly runs bash for single-user mode, there's no way for
SELinux to set the proper context (to distinguish it from other init scripts).
Inserting a helper binary in the way allows for this.

While we're changing this, we make it configurable so it's easily possible
for people to use sulogin if they so desire.

Adjust other jobs accordingly.

Use a configuration parameter for what ttys to start.

Don't try to start rhgb.

(and off by default) (#198695, #196179, #196208)