added column comment to the Sale model
- added field comment to the new/edit sale page
- adjusted the view of the new/edit sale page
added keypad support
to add new keypad to a field, just mark it with class "keypad"
added keypad to search, amount and price field
Merge stuff from Noah, it would probably be nice if the comment field could be toggled, so that it only consumes space if it is really needed