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>