Bug 21746: Remove NO_LIBRARY_SET

Bug 21746: Remove NO_LIBRARY_SET

NO_LIBRARY_SET was used when the DB user was logged in. Since bug 20489
it's not longer possible. We could remove the code.

One occurrence left in C4::InstallAuth as there is no (real) logged in user yet.

Test plan:
* Install Koha to make sure NO_LIBRARY_SET is not needed during the
install process
* Login into Koha
* Make sure the your library's name is displayed correctly in the header
* Set another library
* Confirm that the library's name is updated

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
No problem during install, nor changing library.
Fixed (pre-existing) tab in circ/branchtransfers.pl
No errors

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