No, minimum for server/virtual machine is licenses for 4 core, downgrade rights are part of volume licensing, you can read details in Product Use Rights (PUR). http://www.microsoft.com/en-us/Licensing/product-licensing/products.aspx

http://sql2014.pl/docs/SQL_Server_2014_Licensing_Guide.pdf

http://blogs.technet.com/b/volume-licensing/archive/2014/05/29/licensing-how-to-sql-2014-licensing-changes.aspx