decruft: remove last dead .fa rule (.footer span.fa:hover)

Footer icons are sprites now; no .fa elements remain. FontAwesome is fully gone
from the theme — 0 references in templates, CSS, and the bundle.

style.css

@@ -806,10 +806,6 @@ img.dw {
 	color: #FFFFFF;
 	text-decoration: none;
 }
-.footer span.fa:hover {
-	color: #FFFFFF;
-	text-decoration: none;
-}
 p.cc {
 	float: right;
 	font-size: 14px;