Run Elixir/Phoenix tests and release builds (for CI)
Version tags indicate version of Elixir, everything else is the latest stable version that works with that version of Elixir at the time of building.
Tag 1.4.5 contains:
Erlang (20.0) Elixir (1.4.5) Node (8.1.2) Yarn (0.24.6)
Docker Pull Command