Log Message:
Update SOGo to 2.3.20.

2.3.20 (2017-03-10)
-------------------

New features
 - [core] new sogo-tool checkup command to make sure user's data is sane
 - [core] new sogo-tool manage-acl command to manage calendar/address book ACLs
 - [web] use "date" extension of Sieve to enable/disable vacation \ 
auto-reply (#1530, #1949)

Enhancements
 - [web] added Hebrew (he) translation - thanks to Raz Aidlitz
 - [web] updated CKEditor to version 4.6.2

Bug fixes
 - [core] remove all alarms before sending IMIP replies (#3925)
 - [core] fixed handling of exdates and proper intersection for fbinfo (#4051)
 - [core] remove attendees that have the same identity as the organizer (#3905)
 - [eas] improved EAS parameters parsing (#4003)
 - [eas] properly handle canceled appointments
 - [web] fixed SCAYT automatic language selection in HTML editor
 - [web] prevent 304 HTTP status code for Ajax requests on IE (#4066)