Use correct library versions in requirements.txt

[Aid91]

Datastream.io is not working because some of the library dependencies are not set to the correct version (tornado and elasticsearch in my case).
Here is the pip freeze (python3.5) of the fully working datastream.io:

bokeh==1.3.0 dateparser==0.7.1 -e git+https://github.com/MentatInnovations/datastream.io@a243b89ec3c4e06473b5004c498c472ffd37ead2#egg=dsio elasticsearch==5.5.3 Jinja2==2.10.1 joblib==0.13.2 kibana-dashboard-api==0.1.2 MarkupSafe==1.1.1 numpy==1.17.0 packaging==19.0 pandas==0.24.2 Pillow==6.1.0 pyparsing==2.4.1.1 python-dateutil==2.8.0 pytz==2019.1 PyYAML==5.1.1 regex==2019.6.8 scikit-learn==0.21.2 scipy==1.3.0 six==1.12.0 tornado==4.5.3 tzlocal==2.0.0 urllib3==1.25.3