MIX_ENV=dev mix deps.get fails

[skull-squadron]

** (Mix) command git clone --no-checkout "https://github.com/josevalim/dynamo.git" "deps/dynamo" failed

[skull-squadron]

Updated mix.exs as follows, still a problem running mix server:

Unchecked dependencies for environment dev:
* exjson [git: "https://github.com/guedes/exjson.git"]
  could not find app file at deps/exjson/ebin/exjson.app

mix.exs

    [ { :mimetypes, %r(.*), github: "spawngrid/mimetypes" },
      { :ranch,  %r(.*), github: "extend/ranch" },
      { :cowboy, %r(.*), github: "extend/cowboy" },
      { :dynamo, "0.1.0.dev", github: "elixir-lang/dynamo" },
      { :exjson, github: "guedes/exjson" } ]