[onewire] increased the delay value for conversion

- If the DS18B20 is having output od 85 deg. C this change helps
- tested with two separate devices on two separate systems with a same result
[onewire] more devel friendly

- added more debug messages
- added a few debug hints for newbies
- added code to print temperature with higher resolution
Merge pull request #5 from hecko/master

two commits - one semi-bug, one improvement