1) Fix error of showing category
- Kevin needs to change the code which should add "category" to DB.
- For now, it doesn't show the category but only shows the list of
items.
- Change the category part in CashierWeb.java

2) Fix error of showing category list in Spinner
- Add categories to strings.xml
- Change Spinner part in sl_item_detail.xml

3) Fix error of parsing price for Integer
- change from Integer.parseInt to Float.parseFloat in
SLItemViewAdapter.java