Merge ModelsBuilder in, NuGet dies on circ dependencies now

src/Umbraco.ModelsBuilder/ModelsUsingAttribute.cs

@@ -0,0 +1,21 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Security.Policy;
+using System.Text;
+using System.Threading.Tasks;
+using Umbraco.ModelsBuilder;
+
+namespace Umbraco.ModelsBuilder
+{
+    /// <summary>
+    /// Indicates namespaces that should be used in generated models (in using clauses).
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Assembly, AllowMultiple = true, Inherited = false)]
+    public sealed class ModelsUsingAttribute : Attribute
+    {
+        public ModelsUsingAttribute(string usingNamespace)
+        {}
+    }
+}
+