Update 3/6/2015 This issue has been reported fixed.
I just submitted an issue for EF7 on GitHub. The latest versions of EF7 nightly have an issue how the foreign key is scripted for creating in SQL Server.
2/16/2015 I updated the blog series to compensate for any issue!
This was causing an Incorrect Syntax error when you try to apply the InitialMigration in blog series.