wrap scapy with explicit imports

pylint can't handle scapy's magical imports.
diff --git a/src/python/oftest/test_parse.py b/src/python/oftest/test_parse.py
index 7143350..b6c8fce 100755
--- a/src/python/oftest/test_parse.py
+++ b/src/python/oftest/test_parse.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 import unittest
 import parse
-import scapy.all as scapy
+import packet as scapy
 
 class TestPacketToFlowMatchV3(unittest.TestCase):
     def test_tcp(self):