Update to 2.8.5

Upstream changes:
Highlights
MDL-35392 - Feedback from module assign is now always shown in the gradebook
MDL-31036 - No more truncating characters in assignment quick grading
MDL-46626 - Log report export no longer contains html
MDL-23273 - Limit of responses in choice module is respected in case of synchronous submissions
Functional changes
MDL-31578 - Shibboleth can map attributes for all Moodle fields including custom attributes
MDL-47911 - Performance improvement on gradebook operations
MDL-49240 - Web service core_get_string now functions correctly
MDL-45621 - It is possible to uninstall portfolio plugins
MDL-48670 - Standard behat tests now work properly regardless of user timezone
UI changes
MDL-48533 - Backup report now links to the individual course backup summaries
MDL-49064 - left-align css class now has an RTL equivalent in bootstrap base
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-42138 - Required custom profile fields are always required on signup form even when user has logged in as guest
MDL-49059 - Possible to embed YouTube videos with start time or playlist info
MDL-48544 - Block region no longer disappears if all blocks in it were hidden
MDL-48841 - Fixed bug with not being able to reset scheduled task to defaults
MDL-49167 - Fixed regression with $CFG->yuislasharguments introduced by previous minor release
MDL-47953 - Grader report shows correct number of students per page when suspended users are present
MDL-48294 - enablemobilewebservice is no longer duplicated in Site admin
MDL-48679 - Fixed bug with missing grade export URL when using grade publishing


(wen)