Bug 16739: Show note instead of 500 error for 'Generate EDIFACT' when no EDI account...

Bug 16739: Show note instead of 500 error for 'Generate EDIFACT' when no EDI account is configured

When a book seller (vendor) does not have EDI account information configured
the basketgroup display still shows a button to generate EDIFACT output which
results in 500 error when clicked.  This patch fixes two aspects of this:

a) it stops the button being displayed in the first place, replacing it with
a message that explains there is not EDIFACT configuration for the vendor.

b) if, somehow, an edifact print operation is passed to the basketgroup
script it detects the lack of an EAN and redirects back to the basket group
display page with a warning message.

To test:
1) Create a vendor with no EDI details.
2) Create a basket with some items in, then close it and add it to a basket
   group for this vendor.
   3) Go to that vendor's basket groups, click on the "Closed" tab and then
      click on the 'generate edifact order' button. You should get a 500 error.
   4) Apply this patch.
   5) Repeat 3, except this time you should find that the 'generate edifact
      order' button has been replaced with a note that there is
      "No EDIFACT configuration for <vendor>".

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>