wacom: Add work-around for configs on NFS shared homes

When sharing the same home directory over NFS, it might be convenient
to share device configurations as well, so that the "Wacom Intuos X" on
machine A has the same configuration as "Wacom Intuos X" on machine B
for that user.

The work-around makes the machine-id be all zeroes when
~/.config/gnome-settings-daemon/no-per-machine-config
and as such, should not be applied during a running GNOME session.

https://bugzilla.gnome.org/show_bug.cgi?id=723099
keyboard: Apply num-lock to newly connected keyboards

before 34395459cc8f0da6f163736743bced441ef86390, apply_all_settings()
and then apply_numlock() would sync up the numlock LED on a newly
hotplugged device.
34395459cc8f0da6f163736743bced441ef86390 removed that call, so devices
now come up with the numlock LED off even when the numlock is on, and a
subsequent state change will wrongly toggle it, i.e. LED off when numlock
is on, LED on when numlock is off.

This should really be fixed in the xserver but it's unlikely to happen,
restoring this patch in gnome-settings-daemon seems the simplest solution
for now.

https://bugzilla.gnome.org/show_bug.cgi?id=722753
Revert "Revert "Adding shortcut for toggle screen reader""

This reverts commit 11c0be5410caf47adaa968fb852f4a1f62210bde.

Wrong keybinding.