screencast: Don't leak recorders on failure

ShellRecorder.record() may fail, remove the recorder from the map
in that case.

https://bugzilla.gnome.org/show_bug.cgi?id=737846
screencast: Re-add lockdown support

Commit 81bb7009ea120d3 removed support for the disable-disk-writes
lockdown feature for screencasts, add it back.

https://bugzilla.gnome.org/show_bug.cgi?id=737846
screenshot: Respect lockdown settings

We allow users/admins to lock down disk writes, respect that when
taking screenshots.

https://bugzilla.gnome.org/show_bug.cgi?id=737846
Updated Portuguese translation
Updated Spanish translation
userWidget: Respect the scale factor in the bin size we set

Otherwise, the widget will be too small on hi-DPI devices.

Based on a patch by: Darcy Beurle <darcy@beurle.id.au>

https://bugzilla.gnome.org/show_bug.cgi?id=735419
layout: Add the feedback group to the uiGroup

This makes DND under Wayland visible under the magnifier.
screenShield: focus login screen after lifting shield

This commit ensures the login screen gets focused after
the screen shield is raised.

The code affects the unlock screen as well, but it's
less important since the unlock screen gets destroyed
and recreated each time the curtain moves, so it
has an opportunity to take focus on its own.

https://bugzilla.gnome.org/show_bug.cgi?id=708105