Merge branch 'serials_mods' of git://github.com/colinsc/koha into to-push

Description by Colin Campbell:

A number of commits, subsequent to enabling warnings in C4::Serials and
eradicating errors and removing dead code.
These are extracted from an install branch running at UN FAO in Rome.
Commits have been rebased on current 3.2 HEAD.
These are not major new functionality, but  a series of fixes to
eradicate some randomness caused by undefined values. Includes a commit
to fix Licenses in the serials directory.

* 'serials_mods' of git://github.com/colinsc/koha:
  Check value is defined before splitting it
  Fix FSF Address in directory serials/
  Bug 4380 Use syspref to resolve which bib display is used
  Remove bottleneck making claims page unuseable
  Clean up Pod Documentation
  add warnings to Serials.pm
  Add Text to claim date column's header
  Basic refactoring of serials-edit.pm
  Remove unused or unnecessary variables in claims processing

Signed-off-by: Galen Charlton <gmcharlt@gmail.com>