Book provider docs

[Ragazzo]

Book provider in docs should be fixed, because it cant generate 13 length numbers due to restriction of mt_getrandmax(), if i run Book provider from docs like below:

 public function ISBN()
{
    return $this->generator->randomNumber(13);
}

i got following exception:

InvalidArgumentException: randomNumber() can only generate numbers up to mt_getrandmax()

so it should be fixed and noted in docs. Or is there anything i am missing and this setting can be configured somehow? For now i got:

var_dump(mt_getrandmax()); //int(2147483647)

P.S. Ubuntu 13.04, php 5.5.3

[fzaninotto]

I also fixed another wrong ISBN generator in the docs in eb28eb0