Bug 26312: Catch ES Client errors, log, and continue indexing when error encountered

Bug 26312: Catch ES Client errors, log, and continue indexing when error encountered

This catches a timeout response from the ES server, logs this, and continues the indexing

To test:
1 - perl misc/search_tools/rebuild_elasticsearch.pl
2 - Make the ES server timeout (I don't have good instruction yet)
3 - Watch the job crash
4 - Apply patches
5 - perl misc/search_tools/rebuild_elasticsearch.pl
6 - Make the server timeout
7 - Note the job reports failed commit, and continues

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Joonas Kylmälä <joonas.kylmala@helsinki.fi>
Bug 26312: (follow-up) Reset buffers even if commit fails

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Joonas Kylmälä <joonas.kylmala@helsinki.fi>
Bug 26312: (follow-up) Fix whitespace and missing semicolon

Signed-off-by: Joonas Kylmälä <joonas.kylmala@helsinki.fi>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>