gtkgreet 0.7

This release includes the ability to style gtkgreet with stylesheets and
background images, automatic gtk-layer-shell detection, and a few other
improvements.

Aleksei Bavshin (5):
      Fix --command argument for builds without layer-shell
      Use layer-shell anchors to fill the screen
      Add support for user CSS styles.
      man changes for --style option
      Convert -Dlayershell to 'feature'

Kenny Levinsen (5):
      Remove action_quit
      Add support for background images
      man: Document the background image flag
      Remove gtk-application-prefer-dark-theme
      ci: Disable automatic github mirroring