Add a first async test

.travis.yml

@@ -13,12 +13,12 @@ addons:
 install:
 - ./install_ta-lib.sh
 - export LD_LIBRARY_PATH=/usr/local/lib:$LD_LIBRARY_PATH
-- pip install --upgrade flake8 coveralls pytest-random-order mypy
+- pip install --upgrade flake8 coveralls pytest-random-order pytest-asyncio mypy
 - pip install -r requirements.txt
 - pip install -e .
 jobs:
   include:
-    - script: 
+    - script:
       - pytest --cov=freqtrade --cov-config=.coveragerc freqtrade/tests/
       - coveralls
     - script: