INTEG-214 [integ-calendar][Migration] Broken Activity Stream due to deleted events

Fix description: Don't show deleted event on activity stream.
SWF-2923 : Create pkg-improv branch and update projects versions
Use maven-parent-pom 13-SNAPSHOT
PLF-5900 : Use EXOGTN for eXo Platform Community
PLF-5684 : Declare the source release package used to bundle all PLF sources