Use phoenix and elixir version from mix.exs in task to create new phoeni...

...x apps. To avoid updating the template every time phoenix or elixir versions are changed.
This will get the config of the current mix project when the code is run, which wont exist since you are creating a new mix project. If you `unquote` `Keyword.get(Mix.Project.config, ...)` it will get the mix config when phoenix is being compiled.