create MPSPrinterList object
add locationManager and printer access function to MPSPrinterList
add MPSPrinterList to all controllers that need printers
pass down MPSPrinterList down to controllers that need them
make app use MPSPrinterList
get rid of code that is no irrelavent with swtich to MPSPrinterList
change casting
make locationManager a property in MPSTabController