Merge ModelsBuilder in, NuGet dies on circ dependencies now

src/Umbraco.ModelsBuilder/ModelsBaseClassAttribute.cs

@@ -0,0 +1,16 @@
+using System;
+
+namespace Umbraco.ModelsBuilder
+{
+    /// <summary>
+    /// Indicates the default base class for models.
+    /// </summary>
+    /// <remarks>Otherwise it is PublishedContentModel. Would make sense to inherit from PublishedContentModel.</remarks>
+    [AttributeUsage(AttributeTargets.Assembly, AllowMultiple = false, Inherited = false)]
+    public sealed class ModelsBaseClassAttribute : Attribute
+    {
+        public ModelsBaseClassAttribute(Type type)
+        {}
+    }
+}
+