add :mssql_unicode_strings opt to mssql db's to enable/disable unicode prefix
This change can greatly improve the speed of queries using older versions of mssql. In my testing, I got speed up's of 10x-100x. I couldn't come to a good solution to update Database#initialize and Dataset#initialize in lib/adapters/shared/mssql.rb, so the code for setting the option is found in the ADO, JDBC and ODBC adapters
add :mssql_unicode_strings opt to mssql db's to enable/disable unicod…
This looks good. I'll probably refactor it a little, but as long as the tests pass, it'll go in. Thanks!