Functional test for editing pricing

Mainly, I implement editing sales items with pricing.  Doing so, I
detected a lot of errors which are fixed now:

- Use the new display of error messages for cascading items.
- Prevent selection of invalid types in step 1 pricing table.
- Prevent moving items in step 1 pricing table if computability would
  be impossible.
- Prevent selection of invalid rows when in finder mode.
- Display error messages (alerts) when trying to remove referenced
  items or move illegally instead of simply doing nothing.
- Remove the use of the array _itemReferences in CoffeeScript.  All
  item references are not obtained from the hidden input controls,
  only.
- Fix an error in JavaScript where <select> controls are selected by ID
  when using document.forms[...].elements[...].  This can be prevented
  by specifying an empty ID for these <select> controls.
- Fix a bug in I18nController which generates invalid JavaScript if
  message resource strings contain quotes or backslashes.
- Add the missing "create" button to the product and service show 
  views.
- Fix a bug in functional test case when entering values into non-empty
  input controls: now all characters are deleting by sending the
  backstep key.