BigInteger: make it so you can do $min->random($max)

...and $min->randomPrime($max) as well
BigInteger: fix syntax error
BigInteger: fix unit tests
BigInteger: change argument names for random / randomPrime
BigInteger: unit test update
BigInteger: update comments
BigInteger: one more change to the comments
Merge pull request #373 from terrafrost/another-random-change

BigInteger: make it so you can do $min->random($max)

* terrafrost/another-random-change:
  BigInteger: one more change to the comments
  BigInteger: update comments
  BigInteger: unit test update
  BigInteger: change argument names for random / randomPrime
  BigInteger: fix unit tests
  BigInteger: fix syntax error
  BigInteger: make it so you can do $min->random($max)