Use %r in __repr__.

Suggested by @exhuma in [code review][].
---
[code review]: 9c48287#commitcomment-2904330

Author: bd808

src/iptools/__init__.py

@@ -640,7 +640,7 @@ def __repr__ (self):
         >>> repr(IpRange('127.0.0.255', '127.0.0.0'))
         "IpRange('127.0.0.0', '127.0.0.255')"
         """
-        return "IpRange('%s', '%s')" % (
+        return "IpRange(%r, %r)" % (
                 long2ip(self.startIp), long2ip(self.endIp))
     #end __repr__