Updated CHANGES.md

Updating details in advance before version bump.

Also minor fixes to previously listed changes.

CHANGES.md

@@ -2,7 +2,26 @@
 
 All notable changes to this project will be documented in this file.
 
+## [3.1.16] - 2017-09-04
+### Added
+- New digital signature element (uses existing functionality in the TCPDF library).
+- Ability to duplicate site templates via the manage templates page.
+- Ability to delete issued certificates for individual users on the course report page.
+
+### Changed
+- Removed usage of magic getter and abuse of ```$this->element```. The variable ```$this->element``` will still be
+  accessible by any third-party element plugins, though this is discouraged and the appropriate ```get_xxx()```
+  method should be used instead. Using ```$this->element``` in ```definition_after_data()``` will no longer work.
+  Please explicitly set the value of any custom fields you have in the form.
+
+### Fixed
+- Added missing ```confirm_sesskey()``` checks.
+- Minor bug fixes.
+
 ## [3.1.15] - 2017-08-11
+### Added
+- Added much needed Behat test coverage.
+
 ### Changed
 - Minor language string changes.
 - Made changes to the UI when editing a certificate.
@@ -10,8 +29,9 @@ All notable changes to this project will be documented in this file.
   - Added icon next to the 'Delete page' link.
   - Changed the 'Add page' button to a link, added an icon and moved it's location to the right.
   - Do not make all submit buttons primary. MDL-59740 needs to be applied to your Moodle install in order to notice the change.
-- Fixed issue where the date an activity was graded was not displaying at all.
-- Added much needed Behat test coverage.
+
+### Fixed
+- Issue where the date an activity was graded was not displaying at all.
 
 ## [3.1.14] - 2017-08-05
 ### Changed