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.
Add __MigrationHistory table.

This table is needed for EF migrations. Migrations also require the data
in this table, so that will need to be ported over somehow.
Update Database Project with Voting changes.

Add the new tables and fix the constraints in the Sessions table.
Update dbproj file.

Missed this in the previous commits.
Set the target platform to be SQL Azure.

SQL Azure supports only a subset of SQL Server 2012 functionality, so we
don't want to end up relying on a feature we can't use.
Add existing migrations to the database project.

I don't know whether a post-deployment script is the appropriate
mechanism for this, but it works for now. There's a high probability
that using this approach will mean ensuring this script is updated with
all future migrations, which is unsustainable.
Merge pull request #138 from alastairs/database-project

Database Project updated with latest schema and __MigrationHistory table data.