BibIndex: move helper functions to utils file

* Moves some of the helper functions from bibindex_engine
  to bibindex_engine_utils file.

Signed-off-by: <grzegorz.szpura@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>
BibIndex: WordTable API changes

* Removes 'fields_to_index' argument from WordTable's argument
  list.

Signed-off-by: <grzegorz.szpura@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>
BibIndex: abstraction layer for terms retrieval

* Introduces new TermCollector class which
  handles terms retrieval from different
  part of the system.

Signed-off-by: Grzegorz Szpura <grzegorz.szpura@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>
BibIndex: indexing non-MARC standards

* Introduces NonMarcTermCollector for acquiring data
  from non-MARC records.

* Adds new column to tag table and inserts
  corresponding RecJson fields as another
  non-MARC value for 'tag'.

* Enhances test suite acordingly.

Signed-off-by: Grzegorz Szpura <grzegorz.szpura@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>
BibIndex: recjson fields in admin interface

* Admin interface shows recjson fields
  in logical fields overview.

* Fields and tags are shown directly in index
  overview.

* Edition of tag enhanced with option to
  change value for recjson field.

Signed-off-by: Grzegorz Szpura <grzegorz.szpura@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>
BibField: fix copyright field names

* Fixes a typo for one of the copyright fields and also changes its name
  to `copyright_status` to avoid duplicate names.  (closes #1933)

Signed-off-by: Esteban J. G. Gabancho <esteban.gabancho@gmail.com>
Reviewed-by: Tibor Simko <tibor.simko@cern.ch>
installation: location of demo_table_jui.css

* Fixes location of demo_table_jui.css by explicitly referencing last
  git tag that contained the file.

Signed-off-by: Samuele Kaplun <samuele.kaplun@cern.ch>
Merge pull request #1954 from kaplun/fix-install-demo_table_jui

installation: location of demo_table_jui.css