Utilize parameterized logging and remove toString() calls

Utilize parameterized logging and remove toString() calls

As suggested in the SLF4J FAQ:
https://www.slf4j.org/faq.html#logging_performance
.. parameterized logging can improve the efficiency of logger calls when
logging at the specified level is disabled.

In addition, per the FAQ: https://www.slf4j.org/faq.html#paramException
since SLF4J 1.6.0 it is possible to use parameterized logging and also
log an exception/throwable.

toString() is called automatically:
https://www.slf4j.org/faq.html#string_contents

These changes were suggested by SLF4J Helper for NetBeans IDE:
http://plugins.netbeans.org/plugin/72557/