Fix varchar and text types in SqlServerDriver
Lighthouse #22: http://liftweb.lighthouseapp.com/projects/26102/tickets/22
The current types won't store unicode data according to the docs. Also, there's a change from TEXT to VARCHAR(MAX) for text type data in Sql Server 2005 and up.
Just checked this on 2005 sql server, ship it on review board.
Imported from GitHub: http://github.com/dpp/liftweb/issues/16/find
Imported from Assembla: http://www.assembla.com/spaces/liftweb/tickets/16