Merge pull request #217 from martin-grofcik/5.15-SNAP

ACT-1712 Duplicate task when signal is sent to User Task
surrounded execute method with try/catch to prevent other locked jobId's from failing to execute
fixed silly copy paste error in logger factory method
fix act-1868
Merge pull request #220 from smirzai/act-1868

fix act-1868
ACT-1935: BeanELResolver hides target exception in ELException when catching InvocationTargetException
Merge branch 'master' of https://github.com/Activiti/Activiti
Doc fix, see https://github.com/Activiti/Activiti/commit/a2670adef73501734d4341761049e3fe482d71b7#commitcomment-5541809
Merge pull request #219 from rmberg/job-exception-handling

Added ExecuteJobsRunnable exception handling
Switched names of form-type classes
ProcessInstance start event fix