jAustin hw1 submission

The play-again feature works by checking if number of guesses left is 0, which is a little redundant considering the while(num_chances > 0) loop. Outside of this style issue, the program works for the specification and challenges.
We already know that user_guess is an integer, so it might just be simpler to write
"if user_guess < 1 or user_guess > max_num"