updated .travis.yml for faster tests

.travis.yml

@@ -1,11 +1,13 @@
 language: python
 python:
  - "2.7"
-sudo: required
-before_install:
- - "ifconfig"
- - "sudo apt-get update -qq"
- - "sudo apt-get install tcpdump libpcap0.8-dev libnetfilter-queue-dev libssl-dev"
+
+addons:
+  apt:
+    packages:
+    - libpcap0.8-dev
+    - libnetfilter-queue-dev
+    - libssl-dev
 
 install: "pip install -r requirements.txt"
-script: nosetests
+script: nosetests