Include adwaita-theme into the extension.

Since probably Gnome-Shell 3.8 extension theme can overwrite default values.
There is no need anymore for a dedicated theme. I import it here and
enable/disable it by controlling a css class.
Add settings for the theme customisation.
Always apply custom opacity.

Remove the option to apply custom opacity only when in autohide.
Remove background opacity code
Merge branch 'experimental_includetheme' into experimental

Conflicts:
	dockedDash.js