Fix issue #22. Check for undefined with strict comparission
Fix issue #22. Check for undefined with strict comparission

davidBearinTokyo/jQuery.countdown,nsekecharles/count-down,Renji/jQuery.countdown,shiyamkumar/jQuery.countdown,masterweb121/jQuery.countdown,heriwahyudianto/jQuery.countdown,ayann/jQuery.countdown,adrianha/jQuery.countdown,DigitalCoder/jQuery.countdown,baffolobill/jQuery.countdown,loki315zx/jQuery.countdown,fashionsun/jQuery.countdown,tbilous/jQuery.countdown,hilios/jQuery.countdown