Update travis credential

Author: Raymond Yang

.travis.yml

@@ -123,7 +123,7 @@ after_success:
   if [ -n "$TRAVIS_TAG" ]; then
     pip install twine;
     pip install pyOpenSSL ndg-httpsclient pyasn1 || true;
-    python -m twine upload --skip-existing ${TRAVIS_BUILD_DIR}/wheelhouse/*.whl --repository-url $REPO -u $PYPI_USERNAME -p $PYPI_PASSWORD ;
+    python -m twine upload --skip-existing ${TRAVIS_BUILD_DIR}/wheelhouse/*.whl --repository-url $REPO -u $PYPI_USERNAME_TRAVIS -p $PYPI_PASSWORD_TRAVIS ;
     echo "Deployed to PyPI.";
   else
     echo "Not deploying as not a tagged commit.";