checkpw and hashpw should use char[] instead of String parameters

[JoepWeijers]

Hi there,

I am working on a safer implementation of JBcrypt, using char[] instead of Strings as per http://stackoverflow.com/a/8881376.

I would like to publish this new version of JBcrypt and noticed your Github project. Do you appreciate a new implementation in the form of a pull request?

[bric3]

@JoepWeijers How can it be safer with a char array, a structure that is mutable without the help of reflection ?

EDIT: Read the SO question, I didn't thought about memdumps. Really interesting topic !