Meaningful names for backpack actors

Very useful for debugging purposes (like looking into dead letters)
Unique names for procreator and phenotype
Get random parent until parents are different

An easy solution for RouletteWheel problem. Pick first parent randomly then
pick second parent until it's different than the first one. In case if there
is only one phenotype just return Nil (no couples are crated).
Merge pull request #50 from tomrozb/actor-names

Meaningful names for backpack actors
Merge pull request #51 from tomrozb/unique-parents

Get random parent until parents are different
Procreator will mutate with given probability
Remove mutationProbability parameter from procreatorFactory