Bug 28381: Elasticsearch - Add 710 and 711 to default mappings for author index ...

Bug 28381: Elasticsearch - Add 710 and 711 to default mappings for author index (MARC21)

This patch adds fields 710$a and 711$a to the default author mappings for elasticsearch indexing.

To test:
1) Apply patch
2) Reindex using rebuild_elasticsearch.pl -r

If you don't have access to a terminal (in a sandbox for example)
2a) Go to Administration > Search engine configuration, click "Reset mappings"
and confirm
2b) Then reindex

3) Search for an author name found only in 710 using the Author index
in advanced search
4) Repeat search for an author name in 711

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>