Bug 14899: Add the mapping configuration page in the admin module

Bug 14899: Add the mapping configuration page in the admin module

This new page (admin/searchengine/elasticsearch/mappings.pl) will permit
to manage the ES mappings.
For the biblios and authorities indexes, the different mappings can be
managed from this single page.
The interface let you add, remove and update mappings and search fields.
It's also possible to reorder the mappings, as the order can be important
in the indexation process. Note that the table can be displayed in a
different order that the one it was before saving, but the mappings are grouped
by search field and the order inside the search field is preserved.

Limitations:
- If something went wrong during the insertion/deletion/modification,
  the users will loose all these changes.

TODO:
- Add a specific permission (?)
- Add some data checks client side (JS)
- Use checkboxes for facet and suggestible (lazy today...)
- Understand the difference between the 3 values that sortable can have
  and improve the value for the options in the select box.

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>