Make tests run on CI

Specify the entrypoint and cmd on the tester_image2 so that it runs
tests. I was hoping to not have to duplicate the entrypoint and cmd
here, but the results from `docker inspect ${TESTER_IMAGE1_NAME} -f "{{ .Config.Cmd }}"`
were not suitable to pass back to `docker inspect` or `docker run`.

.travis.yml

@@ -32,7 +32,11 @@ before_script:
 script:
   - docker run -d --entrypoint='/bin/sh' -t --name current-atst-tester "${TESTER_IMAGE1_NAME}"
   - docker container exec -t current-atst-tester script/sync-crls
-  - docker commit current-atst-tester "${TESTER_IMAGE2_NAME}"
+  - docker commit
+    --change='ENTRYPOINT ["/usr/bin/dumb-init", "--"]'
+    --change='CMD ["bash", "-c", "${APP_DIR}/script/cibuild"]'
+    current-atst-tester
+    "${TESTER_IMAGE2_NAME}"
   - docker cp current-atst-tester:/opt/atat/atst/crl/. ./crl/
   - docker container stop current-atst-tester
   - docker run --add-host "postgreshost:${postgres_ip}" --add-host "redishost:${redis_ip}" "${TESTER_IMAGE2_NAME}"