opengraph support

lib/wttrin_png.py

@@ -266,6 +266,8 @@ def make_wttrin_query(parsed):
     for key, val in parsed.items():
         args.append('%s=%s' % (key, val))
 
+    args.append('format=png')
+
     url = "http://wttr.in/%s" % location
     if args != []:
         url += "?%s" % ("&".join(args))