textutils: wash_for_utf8() simplification

* Uses '.decode("utf-8", errors)' instead of a while loop.
  (closes #1755)

Signed-off-by: Federico Poli <federico.poli@cern.ch>
Tested-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
BibDocFile: register downloads with recid

* Adds self.recid when calling `register_download()`.
  (closes #1831) (closes #1832)

Signed-off-by: Nikolaos Kasioumis <nikolaos.kasioumis@cern.ch>
Reviewed-by: Tibor Simko <tibor.simko@cern.ch>
WebSearch: fix for 'rhs is of unknown type'

* Fixes TypeError in search_engine that was occurring when a new
  collection has been added but the webcoll has not yet been run.
  (closes #1819)

Signed-off-by: Sebastian Witowski <sebastian.witowski@cern.ch>
Reviewed-by: Tibor Simko <tibor.simko@cern.ch>
mailutils: fix for send_email() error on DEV site

* For the DEV site `send_email()` function was failing while trying to
  concatenate list and string (because the CFG_SITE_ADMIN_EMAIL
  was not a list).  (closes #1744)

Reviewed-by: Tibor Simko <tibor.simko@cern.ch>
Reviewed-by: Yoan Blanc <yoan.blanc@cern.ch>