fix travis build

.travis.yml

@@ -8,6 +8,12 @@ cache:
   directories:
     - $HOME/.cache/pip
 
+addons:
+    apt:
+        packages:
+            - libudev-dev
+            - libusb-1.0-0-dev
+
 python:
     - "2.6"
     - "2.7"
@@ -16,6 +22,9 @@ python:
     - "3.4"
     - "3.5"
 
+before_install:
+   - pip install setuptools --upgrade
+
 install:
     # Optimisation: build requirements as wheels, which get cached by Travis
     - pip install "pip>=7.0" wheel