FIX Changing Dockerfile to fix django import

[AmandaMuniz]

To fix the bug described in issue #169, the Dockerfile was changed.

The changes applied were made in the following lines:

• Line 1 was changed to create the parenting image from python 3;
• Line 2 was added to create an env;
• The following code was deleted because it creates steps that were not necessary.

RUN apt-get update && apt-get install -y --no-install-recommends \
        python3 \
        python3-pip \
        python3-crypto \
        python3-pyodbc \
        python3-setuptools

RUN pip3 install --no-cache-dir toolz

The remaining code was left without changes from the original Dockerfile.