Phoenix CI/CD Guide Outdated, could use editing

Test Phoenix with CI/CD Issues:

  1. Uses outdated Phoenix commands, mix phoenix. -- Phoenix versions >= 1.3 should use mix phx.
  2. The Elixir image referenced in the CI file is outdated (Elixir 1.4) and is no longer maintained; should just use the official image: image: elixir:latest)
  3. before_script should also contain rebar installation
  4. Code in variables: and other sections differs throughout the article
  5. May be useful to add note about adding postgres service reference to mix: for docker users
Edited by Nick West