Bug 5343: Link serial and acqui modules

Bug 5343: Link serial and acqui modules

DB changements:
- Adds 2 fields: subscription.reneweddate and aqorders.subscriptionid.
- Removes 2 unused fields: aqorders.serialid and aqorders.subscription.

Main test plan:
1) Create a subscription
2) Create a bookseller and a basket
3) Add a new order 'from a subscription'
4) Search your subscription and check if results are correct
5) Click on the "order" link
6) Check the biblio information are filled in the form
7) Select a budget and fill some price information.
8) retry steps 3 and 4. Verify you cannot order the same subscription.
Message:Outstanding order (only one order per subscription is allowed).
9) click on your subscription (already added) and check you have a new
table "Acquisition details" with your price information in the "Ordered
amount" line.
10) receive this order
11) On your subscription detail page, the "Spent amount" line must be
filled with your price information.
12) Re order the same subscription. Now you are allowed to. Prices
information have to be filled with the previous information.
13) Retry some orders and click on a maximum of links in order to find a
bug :)

Signed-off-by: Leila Arkab <koha.aixmarseille@gmail.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Comments on last patch.
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>