Build and test backend without docker

Build and test the backend without docker so that tests can be run
against pull requests from forks. Fixes #17

.travis.yml

@@ -30,21 +30,18 @@ jobs:
       script:
         - npm run prettier-check
     - stage: unit test
+      language: python
+      python:
+        - "3.6"
       services:
         - docker
         - postgresql
       addons:
         postgresql: "9.6"
+      before_install:
+        - cd backend
       before_script:
-        - docker login -u _json_key -p "$(echo $GCR_REGSITRY_SERVICE_ACCOUNT | base64 -d)" https://gcr.io
         - psql -c 'create database travis_ci_test;' -U postgres
       script:
-        # need to support branches with / in the their name. Do this by replacing / with -
-        - IMAGE_WITH_TAG=$TEST_IMAGE:${TRAVIS_PULL_REQUEST_BRANCH:-$TRAVIS_BRANCH}
-
-        - docker pull $IMAGE_WITH_TAG || docker pull $TEST_IMAGE:latest || true
-        - docker build --cache-from $IMAGE_WITH_TAG --cache-from $TEST_IMAGE:latest -t $IMAGE_WITH_TAG -t $TEST_IMAGE:latest -f server.Dockerfile .
-        - docker push $IMAGE_WITH_TAG # push this first so we don't have to rebuild if tests fail
-        - docker run --net=host $IMAGE_WITH_TAG python manage.py test -v 2
-        - docker push $TEST_IMAGE:latest
-
+        - cd ..
+        - python manage.py test -v 2