[UPDATE]powertimer behavior after wakeup changed, repetitive powertimers are not changed, log-entrys for the only last 7 days

-powertimer wakeup prevents starting other powertimer (to event end,
60-720 minutes or screen is not in standby)
-repeating timers are not changed stored (changed by recording event or
powertimer wakeup)
-old log-entrys will cleared after 7 days
Merge pull request #47 from iPkay/update

[UPDATE]powertimer behavior after wakeup changed, repetitive powertimers...