simplify travis-ci matrix

Author: ocefpaf

.travis.yml

@@ -11,23 +11,17 @@ matrix:
   include:
   - python: 2.7
     env: TEST_TARGET=default
-  - python: 3.5
-    env: TEST_TARGET=default
   - python: 3.6
     env: TEST_TARGET=default
   - python: 3.6
     env: TEST_TARGET=notebooks
   - python: 3.6
     env: TEST_TARGET=latest_branca
-  - python: 3.6
-    env: TEST_TARGET=latest_branca
   allow_failures:
   - python: 2.7
     env: TEST_TARGET=latest_branca
   - python: 3.6
     env: TEST_TARGET=latest_branca
-  - python: 3.6
-    env: TEST_TARGET=notebooks
 
 before_install:
   - wget http://bit.ly/miniconda -O miniconda.sh