BloomFilter should warn/raise on unrealistic input.

Given an unrealistic combination of number of elements and false positive
probabilitiy, the optimalWidth message should not fail silently. It should
warn the user or throw an exception to ensure that the BloomFilter delivers
the expected performance.
Merge pull request #355 from mweiden/bloomfilter-exception

BloomFilter should warn or raise on unrealistic input.
Merge branch 'develop' into GH-345
Use iterator to prevent unneeded allocation
Remove unneeded Ordering context bound from HeavyHitter case class