Make it possible to schedule jobs to run immediately / with higher precision

When starting jbpm executor jobs the UI only allows you to schedule job to run in the future with 30 minutes increments (at 12:00, 12:30, 13:00 etc).

For testing purposes it would be nice if it was possible to schedule job run with higher precision (at least down to minutes, or possibly seconds). Even better would be if user could specify job to start immediately without delay.