Fix loading of GTK+ theming CSS resources in webapp mode
In webapp mode a different application identifier is used, which causes DzlCssProvider
to derive the wrong resource paths and causes Epiphany's CSS stylesheets to not be loaded. This manually adds the resource path /org/gnome/Epiphany
when running in webapp mode, which results in the CSS snippets being loaded correctly.
Note that the resource path /org/gnome/Epiphany/WebApp
is not removed, but this is not a problem because DzlCssProvider tries all the registered resource paths. As a side effect, we could add different GTK+ styling for webapp mode by placing CSS style sheets in this resource path, if desired.
This fixes bug #15 (closed)