add nose_warnings_filters and nose-timer to all test requirements

rather than just Python 2.7

Author: minrk

.travis.yml

@@ -10,8 +10,8 @@ sudo: false
 install:
     - |
       pip install --upgrade setuptools pip
-      python setup.py bdist_wheel && pip install --pre dist/*.whl
-      pip install ipykernel[test] nose-timer
+      python setup.py bdist_wheel
+      pip install --pre dist/*.whl ipykernel[test]
     - |
       if [[ "$TRAVIS_PYTHON_VERSION" == "3.6" ||  "$TRAVIS_PYTHON_VERSION" == "2.7" ]]; then
         pip install matplotlib

setup.py

@@ -101,7 +101,8 @@
     ]
 
 extras_require = setuptools_args['extras_require'] = {
-    'test:python_version=="2.7"': ['mock', 'nose_warnings_filters'],
+    'test:python_version=="2.7"': ['mock'],
+    'test': ['nose_warnings_filters', 'nose-timer'],
 }
 
 if 'setuptools' in sys.modules: