TST: enable Python 3.5 tests

Author: matthew-brett

.travis.yml

@@ -26,6 +26,7 @@ python:
     - 3.2
     - 3.3
     - 3.4
+    - 3.5
 matrix:
   include:
     - python: 2.7
@@ -47,6 +48,7 @@ before_install:
     - virtualenv --python=python venv
     - source venv/bin/activate
     - python --version # just to check
+    - pip install -U pip  # upgrade to latest pip to find 3.5 wheels
     - pip install nose # always
     - pip install --no-index -f http://travis-wheels.scikit-image.org $DEPENDS
     # pydicom <= 0.9.8 doesn't install on python 3