Bug 19365: Fix several issues with the Elasticsearch code

Bug 19365: Fix several issues with the Elasticsearch code

Also optimize it so it's actually usable.

Test plan:

1. To test it properly you need biblio and authority data. You might get away with enabling AutoCreateAuthorities and BiblioAddsAuthorities so that authorities are created in the process. Another option would be to import authorities first e.g. from LoC.
2. Make sure the authority index has been properly created with "misc/search_tools/rebuild_elastic_search.pl -a -d"
3. Run "misc/link_bibs_to_authorities.pl -v -l" twice and observe the results.

Sponsored-by: National Library of Finland
Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>