#233: Adding ability to put pid in log layout pattern

lib/layouts.js

@@ -145,7 +145,7 @@ function messagePassThroughLayout (loggingEvent) {
  */
 function patternLayout (pattern, tokens) {
   var TTCC_CONVERSION_PATTERN  = "%r %p %c - %m%n";
-  var regex = /%(-?[0-9]+)?(\.?[0-9]+)?([\[\]cdhmnprx%])(\{([^\}]+)\})?|([^%]+)/;
+  var regex = /%(-?[0-9]+)?(\.?[0-9]+)?([\[\]cdhmnprzx%])(\{([^\}]+)\})?|([^%]+)/;
   
   pattern = pattern || TTCC_CONVERSION_PATTERN;