Removed Prefix from MDC key/values, allow override of others, fixed timestamp, increase short message to 255

-Allows for file / line to be overridden enabling custom php error handling scripts to log the original file/line of the
actual error.
-Fixes timestamp not being logged correctly
-Logs the logger name separate from the facility
-Allows facility name to be overridden
-Increases "Short Message" to 255