Run lint from the docker container

We want to run everything, including eslint, from the docker container.
As a next step we would run software tests from the docker container.
Installing the correct version of docker-compose is required, the
default version docker-compose on Travis is older than 3.7.

.travis.yml

@@ -1,18 +1,28 @@
 language: node_js
 node_js:
   - "10"
-services:
-  - docker
 cache:
   yarn: true
   directories:
     - node_modules
+services:
+  - docker
+
+env:
+  - DOCKER_COMPOSE_VERSION=1.23.2
+
+before_install:
+  - sudo rm /usr/local/bin/docker-compose
+  - curl -L https://github.com/docker/compose/releases/download/${DOCKER_COMPOSE_VERSION}/docker-compose-`uname -s`-`uname -m` > docker-compose
+  - chmod +x docker-compose
+  - sudo mv docker-compose /usr/local/bin
 
 install:
   - docker build --build-arg BUILD_COMMIT=$TRAVIS_COMMIT -t humanconnection/nitro-web .
+  - docker-compose up -d
 
 script:
-  - docker run humanconnection/nitro-web yarn run lint
+  - docker-compose exec webapp yarn run lint
 
 after_success:
   # - wget https://raw.githubusercontent.com/DiscordHooks/travis-ci-discord-webhook/master/send.sh