Update .travis after cleaned up requirement.txt.

.travis.yml

@@ -7,8 +7,10 @@ python:
   - "3.5"
 
 # command to install dependencies
-install: 
+install:
   - pip install -r requirements.txt
+  - pip install requests_mock
+  - pip install coverage
   - pip install codecov
 # command to run tests
 script: nosetests --with-coverage --cover-package=ziptastic