Serve static assets from the app itself

Since they will be embedded in the app image, we want the app to always
serve these, not the proxy.

Static assets are moving from this model:

                                                    serve static asset
                                                    ^
                                                    |
    compiled assets volume - (read static asset) -> proxy (nginx)

To this model:

    serve static asset
    ^
    |
    proxy (nginx)
    ^
    |
    (proxy request)
    |
    app (embeds static assets)

We are making the app available on http://localhost:4000 so that devs
can keep the same development workflow.

Proxy is still available on http://localhost, even though static assets
are not being proxied correctly due to Access-Control-Allow-Origin.
Planning on addressing it via
https://medium.com/@yagoazedias_75857/how-to-configure-cors-in-your-phoenix-application-5ef0234bc25f

[#158222089]

README.md

@@ -53,7 +53,7 @@ app_1    | Webpack is watching the files…
 ...
 ```
 
-You can access a dev copy of changelog.com locally, at http://localhost
+You can access a dev copy of changelog.com locally, at http://localhost:4000
 
 Since the app database will be completely empty, you might want to seed it by running the following command: `docker-compose run app mix run priv/repo/seeds.exs`.
 This command resets the app database, please only run it if you are OK losing all data in the app database.

config/dev.exs

@@ -8,7 +8,7 @@ use Mix.Config
 # with brunch.io to recompile .js and .css sources.
 config :changelog, ChangelogWeb.Endpoint,
   http: [port: 4000],
-  static_url: [host: "localhost", port: 80],
+  static_url: [host: "localhost", port: 4000],
   debug_errors: true,
   code_reloader: true,
   cache_static_lookup: false,

docker-compose.yml

@@ -16,8 +16,8 @@ services:
     environment:
       DB_URL: "ecto://postgres@db:5432/changelog_dev"
       VIRTUAL_HOST: "localhost"
-    expose:
-      - "4000"
+    ports:
+      - "4000:4000"
     volumes:
       - ./assets/admin/:/app/assets/admin/
       - ./assets/app/:/app/assets/app/
@@ -47,7 +47,6 @@ services:
       - /var/run/docker.sock:/tmp/docker.sock:ro
       - ./nginx/vhost.d:/etc/nginx/vhost.d:ro
       - ./nginx/conf.d/changelog.conf:/etc/nginx/conf.d/changelog.conf:ro
-      - ./priv/static/:/var/www/static:ro
       - ./priv/uploads/:/var/www/uploads:ro
 
 volumes:

nginx/vhost.d/default

@@ -13,9 +13,6 @@ proxy_max_temp_file_size 0;
 # http://nginx.org/en/docs/http/ngx_http_core_module.html#client_max_body_size
 client_max_body_size 200M;
 
-# Static assets compiled by webpack will be available here
-root /var/www/static;
-
 location ^~ /uploads {
   root /var/www;