Adds *2* approved custom items and updates a custom item

http://baystation12.net/forums/viewtopic.php?f=33&t=10527 for Yankee's
item
http://baystation12.net/forums/viewtopic.php?f=33&t=10850 for
Cataguette's item
http://baystation12.net/forums/viewtopic.php?f=33&t=10952 for Mewthsecuritycats update

/obj/item/clothing/tie/stethoscope/fluff/lucystethos 
/obj/item/weapon/storage/belt/medical/fluff/ems