kvdb updates

OK, done:

* Podspec: you need to change it so it point on YOUR repository, not mine!
* `-[KVDB count]` - Be sure to review how it is/was written, I've left `TODO` comment there.
* I forgot to split the fix `-[KVDB count]` and adding ARC support into separate commits - they are both in `fixes -[KBDV count]` commit.

Once we will be OK with this pull request, I can add some notes about using `kvdb` to README and open an issue where we could discuss possible improvements of `kvdb`.