BibIndex: new country tokenizer, country index, country KB

* Amends SPIRES to Invenio converter to use index cc->country

* Disables SPIRES sintax conversion cc->postalcode

* Adds BibIndexCountryTokenizer

* Adds regression tests for country tokenization on country index

* Adds countrynames-to-country.kb

* Adds country index and country field (in tabfill and with an upgrade
  script)

* Adds command line utility 'kbload', useful to load a new kb from file

* Automatically loads 'countrycode-to-country.kb' when installing demo
  site

* Adds configuration variable CFG_WEBSEARCH_INSTITUTION_COLLECTIONS

* Adds tags 110__u, 371__d, 371__g, 371__x

* Assumes that the country of the institution records does not change.
  If it changes, a manual full reindexing is required.

Signed-off-by: Federico Poli <federico.poli@cern.ch>
Tested-by: Alessio Deiana <alessio.deiana@cern.ch>