Fix taginfo's icon_url (#28)

It needs to be an image file, not a web page.

taginfo.json

@@ -4,7 +4,7 @@
 		"name": "Unroll",
 		"description": "A public transport route explorer",
 		"project_url": "https://github.com/Jungle-Bus/unroll",
-		"icon_url": "https://github.com/Jungle-Bus/unroll/blob/master/img/Logo_Unroll.png",
+		"icon_url": "https://raw.githubusercontent.com/Jungle-Bus/unroll/master/img/Logo_Unroll.png",
 		"contact_name": "Jungle Bus",
 		"contact_email": "[email protected]"
 	},
@@ -152,4 +152,4 @@
 			"description": "Used to fetch additional content from Wikimedia project (images, wikipedia extract, etc)"
 		}
 	]
-}
+}