Fix coverage in travis config

Author: Dan

.travis.yml

@@ -3,10 +3,10 @@ python:
   - "2.7"
 install:
   - pip install -r requirements.txt
+  - pip install coveralls
 script: nosetests --with-coverage --cover-package=pssh
 notifications:
   email:
     on_failure: change
 after_success:
-  - pip install coveralls
   - coveralls