Bug 12054: Inactive vendors should be inactive

Bug 12054: Inactive vendors should be inactive

This patch make inactive vendors really inactive.
That means an inactive vendor would not be able to add a basket / add an order.

Revised test plan
=================

1/ In the acquisition module create 2 vendors: 1 active and 1 inactive.

2/ On the acqui/booksellers.pl, acqui/uncertainprice.pl,
   admin/aqcontract.pl and acqui/supplier.pl (pages which include the
   acq toolbar), you should be able to, for both the 'active' as well
   as the inactive vendor :
     (a) add new basket
     (b) add order items to the basket

   Remark: This is *wrong*. You should be able to do so only for active
           vendor.

3/ Apply the patch

4/ Go to the links in step #2 above and select the inactive vendor
   you should no longer be able to:
   (a) add new basket
   (b) add order items to the basket

   Remark: This is the *correct* behaviour

5/ No change should be noted for vendor marked "active", and should
   be able to undertake operations 4 (a), 4 (b) and 4 (c).

   Remark: This is the *correct* behaviour.

6/ run koha qa tests tool

Bug 12054: (follow-up) Inactive vendors should be inactive

Don't display "add order""block and buttons if the vendor is inactive.

Signed-off-by: Indranil Das Gupta (L2C2 Technologies) <indradg@gmail.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@unc.edu.ar>