ACT-1836: AdvancedCycleBusinessCalendar can handle instances where the scheduled time zone is different from the server time zone and can handle daylight saving time accordingly.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	modules/activiti-engine/src/main/java/org/activiti/engine/impl/calendar/DurationHelper.java
	modules/activiti-engine/src/main/java/org/activiti/engine/impl/util/DefaultClockImpl.java
Interpret ISO date without time zone in the Clock's overridden time zone instead of the server time zone
Fixing upgrade scripts for ASSIGNEE_ column type modification
Moved to 5.15 for release
Merge branch 'master' of https://github.com/Activiti/Activiti
Merge branch 'master' of https://github.com/mwseiden/Activiti
Small changes to pull request
Fix for signal start + variables (tx Fred)
Merge branch 'master' of https://github.com/Activiti/Activiti
Fix for signal start + query (tx Fred)
Added REST-call for global signal event
Merge remote-tracking branch 'upstream/master'