Improve bloom hit rate and usability fixes.

Applied guidelines from:
> Less Hashing, Same Performance: Building a Better Bloom Filter, [Kirsch,Mitzenmacher 2006]

Some basic stats
```
> mean(old_bloom_misses)
[1] 13.25071
> mean(new_bloom_misses)
[1] 1.65624
```

Bloom misses fell drastically in expense of slightly  increased CPU usage:
![old_bloom](https://f.cloud.github.com/assets/169976/876615/a864f444-f8d2-11e2-812f-3b374741964d.png)
![new_bloom](https://f.cloud.github.com/assets/169976/876616/ab2a2dd4-f8d2-11e2-87d5-fc7f4c5bb4e6.png)

**NB!** Those are `Log10` plots