Rerun lineman when coffee/js assets change

This is a hack. Lineman really ought to instead be doing its own
reloading. It watches and compiles the files but doesn't put them in the
right places to be effective. I have not spent the time to learn lineman
well enough to fix it.

Instead as a workaround, restart lineman, because starting lineman puts
everything in its right place.

See exercism#2936 (comment)

docker-compose.yml

@@ -1,4 +1,5 @@
 version: '2.1'
+
 services:
   app:
     extends:
@@ -21,31 +22,27 @@ services:
 
       RACK_ENV:
       DEV_DATABASE_HOST: db
+
   db:
     image: postgres:9.4
     volumes:
       - pgdata:/var/lib/postgresql/data
     environment:
       POSTGRES_USER: exercism
       POSTGRES_PASSWORD: apples
+
   compass:
     extends:
       file: docker/common.yml
       service: app
     command: compass watch
 
-  # Lineman runs, but it's putting all its compiled code into
-  # /frontend/generated, which the Ruby app isn't looking at. On
-  # top of that, it doesn't deal with Docker's SIGTERM in a graceful
-  # way, which slows down stopping the container, so we'll just leave
-  # this whole thing disabled for now.
-
-  #lineman:
-  #  extends:
-  #    file: docker/common.yml
-  #    service: app
-  #  command: lineman run
-  #  working_dir: /exercism/frontend
+  lineman:
+    extends:
+      file: docker/common.yml
+      service: app
+    command: rerun -b --pattern '{**/*.coffee,**/{script,stats}.js}' -- lineman run
+    working_dir: /exercism/frontend
 
 volumes:
   pgdata: