Update CHANGES.md

Update for release.
Admin and hook improvements

Test batteries for hooks.
Improve diagnostics for hooks. Keep logs.
Improve hook installation.
Custom configuations per repositories, not executables.
Configurable `pre-revprop-change` permissions.
Hooks to work best under Subversion 1.8+.
Clean options for hook installation.
Add modified `svnperms.py` in distribution.
Trac 0.12+ changeset added and modified notification.
Trac URL template.
Trac comment edit permission.