Merge branch 'feature/cache-travis' into feature/softchroot

.travis.yml

@@ -3,6 +3,11 @@
 
 language: python
 
+cache:
+  pip: true
+  directories:
+  - lib
+
 # Available Python versions:
 # http://about.travis-ci.org/docs/user/ci-environment/#Python-VM-images
 python:
@@ -20,4 +25,4 @@ script:
   - nosetests headphones
 
 after_success:
-  coveralls
+  coveralls