Block requests not come from trusted_downstream and public non-https requests

.travis.yml

@@ -15,6 +15,7 @@ matrix:
 install:
   - pip install -r requirements.txt
   - pip install pytest pytest-cov codecov flake8
+  - if [[ $TRAVIS_PYTHON_VERSION == '2.7' ]]; then pip install mock; fi
 
 script:
   - pytest --cov=webssh