WebSearch: fix detailed record page tab tracebacks

* Fixes tracebacks in certain detailed record page tabs
  (usage, files, etc).

* Fixes keywords tab that was not showing proper page body.

* Adds regression tests for each tab in order to prevent this error
  from happening again.

Reported-by: Fredrik Nygård Carlsen <me@frecar.no>
Reported-by: Ole Rønning <olerng@gmail.com>
Signed-off-by: Tibor Simko <tibor.simko@cern.ch>
I18N: fix wrong msgids in Persian translation

* Fixes wrong msgid strings in Persian translation.
  Now "msgcmp --use-fuzzy --use-untranslated en.po fa.po"
  yields perfect match.

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>
WebSearch: initial support for recjson output

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>
errorlib:  support for Sentry logging

* Optionally captures exceptions and sends them to the Sentry logging
  platform, if directed by the new CFG_ERRORLIB_SENTRY_URI configuration
  variable. (closes #1726)

* Adds raven python package to requirements-extra

Signed-off-by: Fredrik Nygård Carlsen <me@frecar.no>
Reviewed-by: Tibor Simko <tibor.simko@cern.ch>
Initial commit
Added bfe_authority_links to link to relevant articles about the author
small fixes in styles
brief format style changes
added viaf icon, changed author link in records
added link to authority record in publication authors
implemented functionality and added cfg variables
changed brief format titles of institutes,journals and subjects into links to their record and fixed their css
added count of publication to the authors' record page
minor bug fix
merge