Bug 6875 de-nesting C4/Serials

Bug 6875 de-nesting C4/Serials

* use C4::Branch is loaded only to call GetBranchNAme in PrepareSerialsData
  and set branchname in the hashresult. This sub PrepareSerialsData is used
  in the following scripts :
opac/opac-serial-issues.pl:    my $subscriptioninformation=PrepareSerialsData($subscriptions); => no use of branchname after
serials/serials-collection.pl:   $subscriptions=PrepareSerialsData(\@subscriptioninformation); => no use of branchname after
=> we can remove the ->{branchname} from the result, and remove the C4::Branch dependancy
* moves use C4::Items to require C4::Items, to call AddItemFromMarc, when
  receiving a serial, with Recieving create an item set in the subscription.
* removed use C4::Letters and C4::Search, that are useless

Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>