Update ChangeLog

* Marking this one complete as the Plugin Management interface in now complete and you can now download/upgrade/downgrade/archive/restore plugins from the GUI.

CHANGELOG

@@ -27,6 +27,7 @@ Cacti CHANGELOG
 -issue#5900: Please add the ability to select compiled RRDtool v1.9+
 -feature#412: Import Export for Graph and Tree rules
 -feature#1214: Move Tree Create/Remove/Modify Functions to lib/api_tree.php
+-feature#1398: Implement an interactive web based Plugin upgrade process 
 -feature#1442: Add validation to GUI inputs
 -feature#1523: Value above RRD maximum value
 -feature#1987: Plugins should be able to be downloaded, installed, and upgraded from Plugin Management