Adds dropdown for category on the Product edit view.
Merge branch 'master' into product_category_dropdown
Corrects the type of Product.CategoryId to be a long.  This was
previously an int which disagreed with Category.CategoryId.  This
prevented the Products table from being mapped to the Categories table
correctly when the schema was generated.
Sets the Product.Category and Category.Products properties to be virtual
so they'll be lazy loaded.
Products property is no longer virtual as it apparently wasn't
necessary.
Adds a dropdown to set the category of a product.