Backend package updates

[landswellsong]

• djangorestframework-gis 0.11 has requirement djangorestframework<3.6,>=3.3, but you'll have djangorestframework 3.6.2 which is incompatible suggested by pip
• djangorestframework-filters 0.9.1 has requirement django-filter<1.0,>=0.15.0, but you'll have django-filter 1.0.2 which is incompatible. suggested by pip
• You are using pip version 18.1, however version 19.1.1 is available., part of python:3.6 docker image, either apt-get install pip in the beginning or switch to a newer image?
• djangorestframework>=3.9.1 suggested by GitHub security
• django>=1.11.19 suggested by GitHub security

Suggested branch open in: #291