oauth2 & django-oauth-plus installed only on 2.x

.travis.yml

@@ -14,8 +14,8 @@ env:
 install:
   - pip install $DJANGO
   - pip install defusedxml==0.3
-  - pip install oauth2
-  - pip install django-oauth-plus
+  - "if [[ ${TRAVIS_PYTHON_VERSION::1} != '3' ]]; then pip install oauth2; fi"
+  - "if [[ ${TRAVIS_PYTHON_VERSION::1} != '3' ]]; then pip install django-oauth-plus; fi"
   - "if [[ ${TRAVIS_PYTHON_VERSION::1} != '3' ]]; then pip install django-filter==0.5.4 --use-mirrors; fi"
   - "if [[ ${TRAVIS_PYTHON_VERSION::1} == '3' ]]; then pip install https://github.com/alex/django-filter/tarball/master; fi"
   - export PYTHONPATH=.