New ADOdb driver that extends the standard mssql one. All it does is

New ADOdb driver that extends the standard mssql one. All it does is
to prepend the 'N' char before any SQL literal sent to DB, mainly
because nobody (ODBTP, FreeTDS, ODBC, SQL*Server) seems to be doing
this task, and it prevents, in an high degree true cross-db compatibility.

Once we've moved to prepared statements and some of the developers for
any of the products above (hopefully MS, at server level) will avoid
the 'N', we'll be able to go back to another mssql drivers.

More info at:
  - http://docs.moodle.org/en/XMLDB_Problems (point 8)
  - http://tracker.moodle.org/browse/MDL-6877