Add database project.

Add a SQL Server Data Tools project for the database schema, including an
import of the schema from the MDF file.
Fix SQLProj.
Update schema from live database.

Not really the right way round to do this, but still :smile:
Enable warnings as errors.
Update connection string to use database project.

The database project deploys to a specific LocalDB database, so bung the
generated connection string into the web.config file for debugging
purposes.
Add SSDT build system binaries.

Tweak the .targets and .sqlproj files to reference the correct
locations.