ReverseCase

PROBLEM STATEMENT:

Implement a class ReverseCase, which contains a method reverseCase.  This
method takes a String and returns the String with the case reversed.

DEFINITION
Class name: ReverseCase
Method name: reverseCase
Parameters: String
Returns: String

The method signature is:
String reverseCase(String message);
Be sure you method is public.

TopCoder will ensure the validity of the inputs. Inputs are valid if all of the
following criteria are met:
*The message will contain from 0 (zero) to 50 characters inclusive
*The message will contain the characters 'A-Z', 'a-z', '0-9', inclusive, and
can contain the punctuation characters (see next)
*The valid punctuation characters are  " " (space), "," (comma), "." (period),
"?" (question mark) and "!" (exclamation mark)

Notes:
*Your method should leave all digits (numerals) and all punctuation alone (i.e.
do no manipulation of them).

Examples:
-if the input is "TopCoder", you would return "tOPcODER"
-if the input is "This is Great!", you would return "tHIS IS gREAT!"
-if the input is "ABC, abc, which is better?", you would return "abc, ABC,
WHICH IS BETTER?"
-if the input is "123", you would return "123"
-if the input is "a123a", you would return "A123A"
-if the input is "Your solution is wrong, Fix IT! Is it right then?", you would
return "yOUR SOLUTION IS WRONG, fIX it! iS IT RIGHT THEN?"