Reduce memory cost for Bloom Filter up to ~32 times

[Boiarshinov]

In current realisation of Bloom Filter there is a int value for every array item.

private int [] bitArray;

But the only possible values for that items is 1 or 0, so it would be better to use bit array instead of int array.
There is no bit primitive in Java. boolean values have size of 8 bits so it would be too expensive for our case too. But there is a special collection in standard Java library which can be used as a bit array - BitSet.
BitSet store bits in a long array where every long value used as a container for the next 64 bits.
So it would much more effective for memory usage to use BitSet instead of int array.

[Boiarshinov]

I have prepared Pull Request with such improvement: #3115