Use planemo test --no_cache_galaxy on TravisCI

Author: peterjc

scripts/travis_test.sh

@@ -4,7 +4,5 @@ virtualenv planemo-venv
 . planemo-venv/bin/activate
 pip install planemo
 planemo travis_before_install
- . ${TRAVIS_BUILD_DIR}/.travis/env.sh # source environment created by planemo
-# TODO: Add --no_cache_galaxy once planemo 0.7.0 is available
-# on PyPI.
-planemo test --install_galaxy ${TRAVIS_BUILD_DIR}
+. ${TRAVIS_BUILD_DIR}/.travis/env.sh # source environment created by planemo
+planemo test --install_galaxy --no_cache_galaxy ${TRAVIS_BUILD_DIR}