Random password generator completed, Issue #36

[BrendanBurger]

Hello, I am new to contributing but I worked on Issue #36 Password Generator Function.
I included two methods for generating random strings,was unsure of password requirements.

One method returns a random string of length n with just (upper and lower)characters and at least one digit.
The other method returns a random string of length n with at least one upper character, one special character and one digit.

I also changed the passfield object to a textfield object to view the string.

[GeassCodeBall]

Thanks for your contribution! After reading your code, I think it may be better if we put one set of special character in together with another in the process of adding them into the arraylist. And it may be more convenient when we judge whether the special are added or not. : )