zero length string erases preference + etc

- zero length string preference value erases the preference
- keys and values are not always integers so lines 62, 68 has to be removed
- default value of profiles._debug changed to false so admins won't forget to set it this time(got excessive logging because of it once)
- profile_set works through profile_multiset call
- indent: tabs to spaces
Merge pull request #8 from zlobspb/patch-1

zero length string erases preference + etc