Added plugin entrypoint attribute and interface

essentials-framework/Essentials Core/PepperDashEssentialsBase/Plugins/IPluginDeviceConfig.cs

@@ -0,0 +1,10 @@
+using PepperDash.Core;
+using PepperDash.Essentials.Core.Config;
+
+namespace PepperDash.Essentials.Core.Plugins
+{
+    public interface IPluginDeviceConfig
+    {
+        IKeyed BuildDevice(DeviceConfig dc);
+    }
+}

essentials-framework/Essentials Core/PepperDashEssentialsBase/Plugins/PluginEntrypointAttribute.cs

@@ -0,0 +1,19 @@
+using System;
+
+namespace PepperDash.Essentials.Core.Plugins
+{
+    [AttributeUsage(AttributeTargets.Class)]
+    public sealed class PluginEntryPointAttribute : Attribute
+    {
+        private readonly string _uniqueKey;
+
+        public string UniqueKey {
+            get { return _uniqueKey; }
+        }
+
+        public PluginEntryPointAttribute(string key)
+        {
+            _uniqueKey = key;
+        }
+    }
+}