Tidied up the log and debug methods in LogHelper

Changed the manual null check and String conversion in LogHelper to the static String.valueOf() method, which automatically performs a null check and handles it appropriately. See [String.valueOf(Object)](http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#valueOf(java.lang.Object\))
Merge pull request #608 from SpartaMercenary/master

Tidied up the log and debug methods in LogHelper