Write a program called GradeBook.java. This program should do the following: 1. Prompt the user to enter 3 grades (assume the grades are integer numbers) 2. Compute the average of the 3 grades 3. Print the resulting average (do not worry about rounding the result, just print the value with all of the decimal places) Here is an example of what the program output will look like (italics indicate user input): Grade 1: 89 Grade 2: 93 Grade 3: 72 84.666666667