Added live_num_in_stock method to the variation model for displaying actual number of items available.
Added live_num_in_stock method to the variation model for displaying actual number of items available.

jaywink/cartridge-reservable,syaiful6/cartridge,Parisson/cartridge,syaiful6/cartridge,stephenmcd/cartridge,traxxas/cartridge,traxxas/cartridge,wbtuomela/cartridge,dsanders11/cartridge,Parisson/cartridge,Kniyl/cartridge,dsanders11/cartridge,wbtuomela/cartridge,wyzex/cartridge,wyzex/cartridge,jaywink/cartridge-reservable,wbtuomela/cartridge,traxxas/cartridge,viaregio/cartridge,jaywink/cartridge-reservable,stephenmcd/cartridge,ryneeverett/cartridge,viaregio/cartridge,Kniyl/cartridge,stephenmcd/cartridge,syaiful6/cartridge,dsanders11/cartridge,wyzex/cartridge,ryneeverett/cartridge,ryneeverett/cartridge,Parisson/cartridge,Kniyl/cartridge