Some more plugin stuff, lovely commit messages ikr

src/Artemis.Plugins/Interfaces/IPlugin.cs

@@ -1,6 +1,17 @@
-namespace Artemis.Plugins.Interfaces
+using System.Threading.Tasks;
+
+namespace Artemis.Plugins.Interfaces
 {
     public interface IPlugin
     {
+        /// <summary>
+        ///     Called when the plugin is loaded
+        /// </summary>
+        void LoadPlugin();
+
+        /// <summary>
+        ///     Called when the plugin is unloaded
+        /// </summary>
+        void UnloadPlugin();
     }
 }