ENH: Added upgrade to modules.pip and uptodate to states.pip to control upgrading pip packages
Adding a rename function to all user management modules to rename user accounts.
pkg.removed and purged implements version comparison

One should be able to remove packages only if they match specified version.
Merge pull request #15534 from cimarronm/pip_upgrade

Upgrade functionality for pip module and state
Merge pull request #15538 from garethgreenaway/15511_rename_user

Additions to user mangement modules
Merge pull request #15543 from dr4Ke/pkg_removed_versions

pkg.removed and purged implements version comparison
Merge branch 'develop' of https://github.com/saltstack/salt into iss15537