Log Message:
Update to 3.1.3

Upstream changes:
Moodle 3.1.3 release notes

Functional changes

    MDL-56022 - Assignment: Allow to bulk download students submissions in \ 
separate folders to avoid file renaming confirmations
    MDL-46946 - Prompt users to complete required custom user profile fields \ 
before allowing them to use the site
    MDL-43796 - Assignment: When importing an assignment with blind marking into \ 
another course never reveal identities

API changes

    MDL-52051 - Migrate to Dropbox API v2
    MDL-55602 - Sessions: Add support for Redis as a session_class_handler

Security issues

A number of security related issues were resolved. Details of these issues will \ 
be released after a period of approximately one week to allow system \ 
administrators to safely update to the latest version.
Fixes and improvements

    MDL-47500 - SCORM: Remove blank space on top
    MDL-54852 - Assignment: Do not display "Do you want to leave this \ 
page" dialogue on PDF grading screen when changes are saved
    MDL-29332 - Allow calculated questions to have variables with case \ 
differences (usually affects upgrades from before Moodle 2.1)
    MDL-56129 - Fix video playback with iOS 10.0 and 10.1 devices (iPad / iPhone)
    MDL-29774 - When adding group members and using user search display groups \ 
of potential members
    MDL-42041 - Book: put "Turn editing on" button in a more obvious \ 
location
    MDL-56368 - Fixed alignment of settings for Restrict Access when activity \ 
titles are very long
    MDL-55858 - Remove unsubscribe link from notification email in forum with \ 
forced subscription
    MDL-45969 - PDF annotations now show the submission of the selected attempt \ 
(fixed the bug when only last attempt was shown)
    MDL-55505 - Assignment: Fixed bug when editing grades for previous \ 
submission attempts overwrites existing grades
    MDL-56328 - Bootstrapbase Themes - reduce section activity indent when not \ 
editing