Install ed on Travis

Author: cscorley

.travis.yml

@@ -4,6 +4,9 @@ python:
     - "2.7"
     - "3.3"
     - "3.4"
+before_install:
+    - sudo apt-get update -qq
+    - sudo apt-get install -y ed
 install:
     - pip install .
 script: nosetests