feature request: add uncached option

[thost96]

Hi, it would be very nice to have an option for single sensors or for the whole owfs instance to get the uncached results from owserver for some sensors e.g. to count impulse.

As I could see the uncached directory was ignored at https://github.com/ioBroker/ioBroker.owfs/blob/master/main.js#L144.
Maybe it's possible to get the listing from there as the normal output is cached sometimes for up to 120 seconds which isn't reliable for pir sensors or to count impulses from energy meters.

If you need any more information from owserver please contact me!