Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=54241
Revert the fix for https://issues.apache.org/bugzilla/show_bug.cgi?id=35410 as it is not specification compliant
Remove the remainder of the write(String) method as well as it serves no purpose since it is identical to the method it overrides.
Add some test cases to confirm the expected/correct behaviour
Note: BZ 35410 claims there is no requirement for Object.toString() to be non-null. Many have argued (and I agree) that null is not a String representation and therefore not a valid return value for Object.toString().

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1427804 13f79535-47bb-0310-9956-ffa450edef68