Merge pull request #1596 from chrismccord/improve_enum_take_docs

Add example to Enum.take docs using negative count.
Add heredocs indentation test to DocTest
Make heredocs indentation test pass
Add mismatched indentation test to DocTest
Make mismatched indentation test pass
Add "too much" and "not enough" tests to DocTest
Remove unused variable from DocTest
Merge pull request #1593 from vanstee/string-justification-functions

Implement string justification functions
Update CHANGELOG
Review and deprecate list <-> binary conversion
Quote arguments on elixir/iex help check
Improve docs for iolist_to_binary
Add Path.relative_to_cwd and rely on it when generating stacktraces
Clean up and expose are more complete API in Exception
Handle unsafe vars inside or/and
Add missing helpers file
do_justify should be private
Merge pull request #1600 from devinus/defp-justify

do_justify should be private
Macro.to_string handles access and kw-lists nicer
Merge pull request #1601 from ericmj/macro-tostring-access

Macro.to_string handles access and kw-lists nicer