Issue 4234 - Migrate Discourse to a Docker-based setup

modules/discourse/templates/app.yml.erb

 ## this is the all-in-one, standalone Discourse Docker container template
 ##
 ## After making changes to this file, you MUST rebuild
 ## /var/discourse/launcher rebuild app
 ##
 ## BE *VERY* CAREFUL WHEN EDITING!
 ## YAML FILES ARE SUPER SUPER SENSITIVE TO MISTAKES IN WHITESPACE OR ALIGNMENT!
 ## visit http://www.yamllint.com/ to validate this file as needed
 
 templates:
@@ skipping 10 matching lines @@
   db_default_text_search_config: "pg_catalog.english"
 
   ## Set db_shared_buffers to a max of 25% of the total memory.
   ## will be set automatically by bootstrap based on detected RAM, or you can override
   db_shared_buffers: "256MB"
 
   ## can improve sorting performance, but adds memory usage per-connection
   #db_work_mem: "40MB"
 
   ## Which Git revision should this container use? (default: tests-passed)
-  version: v1.5.3
+  version: v1.6.4
 
 env:
   LANG: en_US.UTF-8
   RUBY_GC_MALLOC_LIMIT: 90000000
 
   ## How many concurrent web requests are supported? Depends on memory and CPU cores.
   ## will be set automatically by bootstrap based on detected CPUs, or you can override
   UNICORN_WORKERS: 2
 
   ## The domain name this Discourse instance will respond to
@@ skipping 37 matching lines @@
     - exec:
         cd: $home/plugins
         cmd:
           #- git clone https://github.com/discourse/docker_manager.git
 
 ## Any custom commands to run after building
 run:
   - exec: echo "Beginning of custom commands"
   - exec: rails r "<% @site_settings.sort_by { |k,v| k }.each do |name, value| %>SiteSetting.<%=name%>='<%=value%>';<% end %>"
   - exec: echo "End of custom commands"