Add support for intersection to BloomFilter.

[b4hand]

I realize that intersection will have the false positive rate of the maximum of the false positive rates of the intersected bloom filters, but this is a useful feature. You already provide support for unions via the merge method.

One concerning thing about the existing union support is that it doesn't check the size of the underlying bitset. This should probably be added to the checks for compatibility purposes before performing a merge. Similarly, it would be nice to add that check for intersection as well.

I'm willing to add code for isCompatible or similar to confirm compatibility before doing merges or intersection if you will allow that change.

[b4hand]

Build is failing for the same reason as #133 which is more evidence that it is unrelated to this code.

[b4hand]

Looking at the build history #108 has the same build failure as well, so it seems highly unlikely that the build failure is due to this code.

[b4hand]

I rebased to the latest master which drops the openjdk7 build, so the build now passes.

[abramsm]

OK to close in favor of #136?