Add compatibilty with OTP 18 typespec changes
Merge pull request #2777 from elixir-lang/emj-otp-18

Add compatibilty with OTP 18 typespec changes
Small fix for Application docs. Returning value is not a tuple
Merge pull request #2778 from pedrosnk/master

Small fix for Application docs. Returning value is not a tuple
Merge branch 'master' of https://github.com/elixir-lang/elixir