Prepare release 3.6.0

CHANGELOG.md

 ## Changelog
 
+### 3.6.0
+  * Add support for Debian 9 (thanks @its-not-a-bug-its-a-feature)
+
 ### 3.5.0
   * Add support for huntgroups (thanks @sts and @phaer)
 

metadata.json

 {
   "name": "jgazeley-freeradius",
-  "version": "3.5.0",
+  "version": "3.6.0",
   "author": "jgazeley",
   "summary": "Install and configure FreeRADIUS",
   "license": "Apache-2.0",