slapos_crm: Ensure you are comparing integers when get value from preference

Also define a short cache, to prevent creation explosion
4 jobs for master in 0 seconds
Status Job ID Name Coverage
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failed SlapOS.Eggs.UnitTest-Master.Python2

00:15:04

failed SlapOS.Eggs.UnitTest-Master.Python3

00:15:22

failed SlapOS.Eggs.UnitTest-Master.Python2

00:12:32

failed SlapOS.Eggs.UnitTest-Master.Python3

00:10:24