There is a new set of tools for performing SQL Server migrations at https://github.com/Schema-Smith/SchemaSmithyFree. They are free to use for small businesses and teams under a community license. All code is available in the repository, no black boxes or hidden anything.

The update process, SchemaQuench, takes a state based approach to update tables. You define the final state you want your table to look like and the update process does whatever alter statements are necessary to get you there. SchemaQuench can apply all of your objects, tables, functions, views, etc as well.

There is also a tool for reverse engineering your database(s) into the expected metadata format all of which can be checked into your repository just like any other code.

Documentation can be found at https://github.com/Schema-Smith/SchemaSmithyFree/wiki