Fix for #890 in Github.
Resetting schedulable table only if necessary.
Moving some test code from the install script test to the settings manager test, since we are not scheduling the master jobs from the install script now.
(Strangely, I get a compilation error saying that there is no CronJobDetail in CronTrigger. Weird, specially since it's the same exact query we had before. Let's see if it passed build.)