Sometimes you want randomness more than reproducability.

Introduce the option to use now() to initialize your rng.

To use, add the following line to your bb config file:
{rng_seed, now}.
move rng_seed default around to make it clearer what it is, any
why someone might want to use a more random seed.
Merge pull request #63 from basho/pevm-randomness

Randomness enhancements.