patch from dkirov to fix TB with gaim presences

src/common/zeroconf/zeroconf.py

@@ -124,6 +124,8 @@ class Zeroconf:
 						key += c
 				else:
 					val += c
+			if val is None: # missing '='
+				val = ''
 			txt_dict[key] = val.decode('utf-8')
 		return txt_dict