Lift font SCSS partials to theme root

This means that themes which include `light/css/_base.scss` (currently Dark and
Status) won't be forced to have Light's font-faces included.  This only really
matters for Status, which uses different fonts throughout.

res/themes/dharma/css/_dharma.scss

@@ -1,5 +1,3 @@
-@import "_fonts.scss";
-
 // XXX: check this?
 /* Nunito lacks combining diacritics, so these will fall through
    to the next font.  Helevetica's diacritics however do not combine

res/themes/dharma/css/dharma.scss

@@ -1,3 +1,3 @@
+@import "_fonts.scss";
 @import "_dharma.scss";
 @import "../../../../res/css/_components.scss";
-