JBPM-4478 - EJB Timer implementation for GlobalSchedulerService

(cherry picked from commit 24ab96f301f029c6bd2f2b0cf167df7309bd6528)
BZ-1171853 - Validate variable type when set

(cherry picked from commit 9acea287a421fb735e931bb45442751b92cb7da2)
migration required changes to be able to run 6.2 on 6.1 and 6.0

(cherry picked from commit 8e8bd9a251df61ae1c4cc87432362d10cbfeabdf)
BZ-1171859 - History data cleanup feature for process / human task

(cherry picked from commit 6505c999f6d92f785619f58c7e6b66b4d4e9233f)