Support on_exit for registering callbacks in ExUnit.
File.rm makes files writeable on Windows before deletion
Revert "EEx tests aware of CR+LF newline on Windows"

This reverts commit f60d3668eda292e6451a059a20f28cb71ce2c0b7.
chmod does not require conversion of bases
Added rm test for read-only files
Fix :io.columns calls
Corrected octal/decimal handling
Add http and https proxy options
Merge pull request #2368 from bkochendorfer/add_proxy_support

Add http and https proxy options
Merge pull request #2367 from chyndman/file-rm-windows-read-write

File.rm makes files writeable on Windows before deletion
Tidy up previous commits
Fix Path.absname("/") to return the absolute path "/", not "".
Add tests for Path.expand("/") to be "/" (the issue is already fixed).
Merge pull request #2370 from keithseahus/master

Fix Path.absname("/") and Path.expand("/") to return the absolute path "/".
Clean up Path and Task code
Remove dependency on manifest files
Fix operator precedence bug in Mix.Compilers.Elixir.clean/1
Merge pull request #2371 from zambal/master

Fix operator precedence bug in Mix.Compilers.Elixir.clean/1
:eaccess becomes :eacces
Merge pull request #2372 from chyndman/eacces-posix-typo

:eaccess becomes :eacces