Properly .gitignore automatically generated rebar_dep/ebin
Mention File.open/2 modes in File.write/3
Add Enum.intersperse
Merge pull request #1878 from pminten/intersperse

Enum.intersperse, change to join
Ensure test fixtures are kept clean
Update release docs task
Automatically handle File.stream and File.binstream based on modes
`mix deps`: Display refs pointing to the checked out commit for each dep
Update the docstring for `mix deps`
Implement tests for git ref formatting