Updated CHANGELOG.md for 1.3.1

CHANGELOG.md

@@ -6,6 +6,25 @@ developers to maintain and readjust their custom modifications on the main proje
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## [1.3.1]
+
+### Added
+
+- #410: Time format from American style to European
+- #441: Added time format selection
+- #452: Provide more information when errors occur during the installation. 
+
+## Fixed
+
+- #433: Selected date when editing an appointment
+- #436: All days unavailable in agendaDay view
+- #438: Error on update process from 1.2.1 to 1.3.0
+- #440: Correct label text for customer phone number in back-end calendar event popup.
+- #453: Unavailable periods not taken into account when more than one customer
+- #455: French Spelling
+- #459: Aggregate Appointment API crashes when a break was added
+- #461: Invalid working plan parsing for foreign languages on day view of the default calendar view.
+
 ## [1.3.0]
 
 ### Added 
@@ -28,7 +47,6 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - #401: Replace loading spinner graphic with a newer one.
 - #403: All calendars will start with Sunday as the first day.
 
-
 ### Fixed
 
 - #155: Appointment management modal is not updated after appointment duration resize.