Use Travis container infrastructure

Author: Juan Luis Cano Rodríguez

.travis.yml

@@ -3,7 +3,6 @@ python:
   - "2.7"
   - "3.3"
 install:
-  - sudo apt-get update
   # We do this conditionally because it saves us some downloading if the
   # version is the same.
   - if [[ "$TRAVIS_PYTHON_VERSION" == "2.7" ]]; then
@@ -24,4 +23,6 @@ install:
   - source activate test-environment
   - python setup.py install
 script:
-  - make test
+  - make test
+
+sudo: false