Support different default time ranges per service

[AlexanderS]

I have some services, that are only checked once per day. I would like to configure a different default_time_range for this services (maybe based on the check command).

I could image some config setting like this:

[check_command1]
default_time_range = "1"
default_time_range_unit = "day"

[check_command2]
default_time_range = "1"
default_time_range_unit = "weeks"

And each not defined check_command should still use the default from ui.default_time_range.