Fixes problem with docker compose and pids file

With pids file available, it prevents the server from starting up whenever docker-compose up is been serve. This link explains the issue better docker/compose#1393

Procfile.dev

@@ -1,2 +1,2 @@
-web: rails s -p 3000 -b 0.0.0.0
+web: bash -c "rm -rf ./tmp/pids/server.pid && bundle exec rails s -p 3000 -b '0.0.0.0'"
 client: sh -c 'bin/client.sh'