update travis install

Author: rusty1s

script/install.sh

@@ -3,8 +3,8 @@
 if [ "${TRAVIS_OS_NAME}" != "windows" ]; then
   python setup.py install
 else
-  echo "python setup.py install"
+  echo "pip install .[test]"
   while sleep 540; do echo "=====[ Still running after $SECONDS seconds ]====="; done &
-  python setup.py install | tail -n 1000
+  pip install .\[test\] | tail -n 1000
   kill %1
 fi

setup.py

@@ -92,6 +92,7 @@ def get_extensions():
     install_requires=install_requires,
     setup_requires=setup_requires,
     tests_require=tests_require,
+    extras_require={'test': tests_require},
     ext_modules=get_extensions() if not BUILD_DOCS else [],
     cmdclass={
         'build_ext':