Adding netifaces pip package.

Change-Id: I94e43bd5726998c89d6f0549e074026e1a5a5f97
diff --git a/requirements.txt b/requirements.txt
index eab3c02..989ae4a 100755
--- a/requirements.txt
+++ b/requirements.txt
@@ -19,7 +19,7 @@
 protobuf-to-dict>=0.1.0
 pyflakes>=1.0.0
 pylint>=1.5.2
-#pypcap>=1.1.5
+pypcap>=1.1.5
 pyOpenSSL>=0.13
 PyYAML>=3.10
 requests