Fixed bug with setup of application.rb settings.
Added HTTPS_ENABLED environment variable to .env.

* By default, this is set to "no" but should be set to "yes". The
  default is used because it's much easier for initial development
  purposes and additional setup for SSL support in development mode
  is outside the scope of this project.
Removed concurrency defaults for application.

* Unless using JRuby or Rubinius, this probably not a standard setup
  for most apps so defaulting this to "false" instead of "true".
Removed Puma server support (replaced with Unicorn).