Update Potlatch 2 to 2.3-88-gc431f56 build

public/potlatch2/imagery.xml

@@ -2,7 +2,7 @@
 
 <imagery>
 	<set>
-		<name>Bing</name>
+		<name>Bing aerial imagery</name>
 		<url>http://ecn.t0.tiles.virtualearth.net/tiles/a$quadkey.jpeg?g=587&mkt=en-gb&n=z</url>
 		<scheme>microsoft</scheme>
 		<sourcetag>Bing</sourcetag>
@@ -16,11 +16,6 @@
         <name>MapQuest Open Aerial</name>
         <url>http://oatile1.mqcdn.com/naip/$z/$x/$y.png</url>
     </set>
-	<set>
-		<name>Yahoo</name>
-		<url>yahoo</url>
-		<sourcetag>yahoo</sourcetag>
-	</set>
 	<set>
 		<name>OSM - Mapnik</name>
 		<url>http://c.tile.openstreetmap.org/$z/$x/$y.png</url>