Bug 10528: add unit tests for C4::Bookseller.pm

The tests are wrapped in a transaction.

NOTE: some tests should pass but doesn't because of incoherences in
the code.  These tests are in comments and preceded by FIXME

Test plan:
prove t/db_dependent/Bookseller.t
t/db_dependent/Bookseller.t .. 15/53
[Some warnings about uninitialised values]
t/db_dependent/Bookseller.t .. ok
All tests successful.
Files=1, Tests=53,  1 wallclock secs ( 0.02 usr  0.00 sys +  0.46 cusr  0.03 csys =  0.51 CPU)
Result: PASS

http://bugs.koha-community.org/show_bug.cgi?id=10528

Signed-off-by: Srdjan <srdjan@catalyst.net.nz>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
The new tests pass nicely, as do all old tests and the QA script.
All patches marked as dependencies have been pushed to master
already.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>