common: Ship a PolicyKit rule for the datetime panel

Allow local admins with an active session use the Date & Time panel
without requiring a password.

https://bugzilla.gnome.org/show_bug.cgi?id=646185
datetime: Alignment fixes for the location marker on timezone map

Make sure the marker is drawn pixel-aligned to avoid fuzziness, and
ensure that it actually ends up in the visible area.

https://bugzilla.gnome.org/show_bug.cgi?id=706253
datetime: New location marker image for the timezone map

The image was drawn by Andreas Nilsson <anilsson@redhat.com>

https://bugzilla.gnome.org/show_bug.cgi?id=706253
datetime: Use g_clear_object()

https://bugzilla.gnome.org/show_bug.cgi?id=706253
datetime: Move pixbuf loading out of the draw signal handler

This moves the timezone location marker image loading code to init()
where most of other resources are loaded, making the draw callback
smaller and easier to read. As a plus, it also avoids needless
allocations during each time the map is drawn.

https://bugzilla.gnome.org/show_bug.cgi?id=706253
privacy: Remove Name & Visibility section

We no longer show the user's name in the GNOME Shell top bar or in the
lock screen and this dialog no longer has any purpose.

https://bugzilla.gnome.org/show_bug.cgi?id=706301
Tajik translation updated