Set windows installer to 0.15.0
Merge pull request #4835 from UtahDave/develop

Set windows installer to 0.15.0
Turn off multiprocessing on Windows for now
Merge pull request #4840 from UtahDave/develop

Turn off multiprocessing on Windows for now
Add link to 64 bit 0.15.0 Windows Salt installer
Merge pull request #4841 from UtahDave/develop

Add link to 64 bit 0.15.0 Windows Salt installer
grammar and spelling fixes to 0.15.0 release notes
Merge pull request #4842 from UtahDave/develop

grammar and spelling fixes to 0.15.0 release notes
fix some release note typos
should fix gemset_empty WRT #4681
Merge pull request #4849 from cvrebert/patch-3

should fix gemset_empty WRT #4681
Merge pull request #4846 from hulu/copyedit-release-notes

fix some typos in the Release Notes
Merge pull request #4833 from 11craft/4830-pkgrepo-managed

Pass `ppa_auth` as a kwarg to `pkg.get_repo` - #4830
Merge branch '4805-pip-no-chown' into using