travis: actually install pylint

.travis.yml

@@ -5,8 +5,8 @@ python:
   - '2.7'
   - '3.4'
   - '3.5'
-#install:
-#  - pip install --quiet -r ci/requirements.txt
+install:
+  - pip install --quiet -r ci/requirements.txt
 #  - git clone https://github.com/"${TRAVIS_REPO_SLUG%%/*}"/qubes-builder ~/qubes-builder
 script:
   - pylint --rcfile=ci/pylintrc qubesmgmt

ci/requirements.txt

@@ -0,0 +1,5 @@
+# WARNING: those requirements are used only for travis-ci.org
+# they SHOULD NOT be used under normal conditions; use system package manager
+docutils
+pylint
+sphinx