Set PostgreSQL password in CircleCI build

The `postgres` Docker image now requires a password to be set. This change sets a password in the CircleCI build to meet that requirement.

See docker-library/postgres#681 for more information.

.circleci/config.yml

@@ -29,8 +29,8 @@ job_defaults: &job_defaults
     ADMIN_OAUTH2_LOGOUT_PATH: '/o/logout'
     ACTIVITY_STREAM_ACCESS_KEY_ID: some-id
     ACTIVITY_STREAM_SECRET_ACCESS_KEY: some-secret
-    DATABASE_URL: postgresql://postgres@localhost/datahub
-    MI_DATABASE_URL: postgresql://postgres@mi-postgres/mi
+    DATABASE_URL: postgresql://postgres:datahub@localhost/datahub
+    MI_DATABASE_URL: postgresql://postgres:datahub@mi-postgres/mi
     DEBUG: 'True'
     DJANGO_SECRET_KEY: changeme
     DJANGO_SETTINGS_MODULE: config.settings.local
@@ -57,12 +57,14 @@ job_defaults: &job_defaults
 
     - image: <<parameters.postgres_image>>
       environment:
-        POSTGRES_DB=datahub
+        POSTGRES_DB: datahub
+        POSTGRES_PASSWORD: datahub
 
     - image: <<parameters.mi_postgres_image>>
       name: mi-postgres
       environment:
-        POSTGRES_DB=mi
+        POSTGRES_DB: mi
+        POSTGRES_PASSWORD: datahub
 
   steps:
     - checkout