add error dialog when cannnot get item data by barcode
add timeout on exhibit
delete debug function
- disable unnecessary picker functions
- alter global alert method into createAlertDialog
- stop scanning when barcode is read successfully
- restart scanning when window or alert dialog is closed
- change timeout parameter
- comonize connection error alert dialog
commonize base url to texchange web site
debug issue #1
commonize error dialog on cannot find item data