Some IO tests return alternate error codes on windows

Now these tests allow different kinds of error codes. However, I currently
duplicate the is_io_error? method; I would assume there would be an easier
way to do this; maybe just put it in a namespace and reference the
namespace?
Merge pull request #1277 from ToJans/WindowsBugfixing

Some IO tests return alternate error codes on windows
Use regex on matching on some of File exceptions
cp_r should pinpoint place of failure on errors
Fixed a bug within File.rm_rf on windows
Fixed unit test for File.Touch with failure on Windows
File.rm_rf! should not complain on invalid entries
Merge pull request #1279 from ToJans/WindowsBugfixing

Windows bugfixing
refactor/rename Macro.to_binary to Macro.to_string with deprecation warning
refactored/renamed from Code.string_to_ast to Code.string_to_quoted
Add Process.self
Merge pull request #1281 from meh/process-self

Add Process.self
Merge pull request #1282 from andrzejsliwa/master

rename of Macro.to_binary and Code.string_to_ast regards to #1143
Update CHANGELOG and minor fixes
cleanup after refactorization of Code.string_to_quoted
Merge pull request #1283 from andrzejsliwa/master

cleanup after refactoring of Code.string_to_qouted
qoute -> quote
No longer support .beam files on mix local
Clean up docs for File
Wording on File's @moduledoc