Fixed the sqlcmd to the latest style.

 * double quotes, property ordering, and bool methods
 * find the installed command path by version/platform using Enumerable#product,
   #map, and #find.
 * Do not default the server to ".", because "localhost" is the default.
 * Do not default the authentication to a trusted connection, because it's the
   default. Let the user work out any error messages/exits from mixed args.
 * Do not default to batch abort mode, make the user specify it.
 * Added ignore vars to disable variable subsitution in specific use cases
   (SQL Server Agent queries, mostly)
 * Fixed variable quoting (-v foo="bar")