Changes to SqlServer drivers

Fixed failing sqlserverschema tests

Change binary column type to VARBINARY(MAX):
SQL Server binary columns have a maximum length of 8000 bytes. Varbinary columns also have a maximum length of 8000 bytes. Varbinary(MAX) columns support up to 2 GB.

Fix for TestFixture to use columnName as the key for the column type array:
It was causing an issue with SqlServer and binary columns in a fixture since SqlServer is quite pedantic on how columns are bound.