build: setup Docker dev configuration

- Add `.dockerignore` file
- Add `Dockerfile.dev`
- Modify `docker-compose.yml`:
  - Add `restart: on-failure` to `app` service
  - Modify `build` section of `app` service
  - Remove `links` section from `app` service
  - Add `networks` section to `app` and `db` services
  - Add `networks` section to the end of the file

Signed-off-by: wancat <wancat@wancat.cc>

.dockerignore

@@ -0,0 +1,2 @@
+node_modules
+.git