- this pymssql test needs to be against the pymssql dialect

- this pymssql test needs to be against the pymssql dialect
- Part of a longer series of fixes needed for pyodbc+
      mssql, a CAST to NVARCHAR(max) has been added to the bound
      parameter for the table name and schema name in all information schema
      queries to avoid the issue of comparing NVARCHAR to NTEXT,
      which seems to be rejected by the ODBC driver in some cases,
      such as FreeTDS (0.91 only?) plus unicode bound parameters being passed.
      The issue seems to be specific to the SQL Server information
      schema tables and the workaround is harmless for those cases
      where the problem doesn't exist in the first place.
[ticket:2355]