Revert "enable kernel output on serial console"

This reverts commit 690fad428a59bcf7601a45c3d294cbc733c50deb,
there is already a config option to do that.
Expose serial console attribute via UI

This also changes back the default to "false",
which works around
https://bugzilla.novell.com/show_bug.cgi?id=860088
Make the tty configurable

Depending on your hardware, common serial consoles could be connected
to ttyS0 or ttyS1. Make it configurable in the proposal (hidden
expert setting)
Merge pull request #256 from dirkmueller/release/roxy/master

Rework serial console settings on node