New: Create methods for handling user group in- or exclusion on project or user action

coscine/issues#328

src/Action/EventArgs/ProjectEventArgs.cs

 using Coscine.Configuration;
+using Coscine.Database.Model;
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -10,10 +11,16 @@ namespace Coscine.Action.EventArgs
     public class ProjectEventArgs : ActionEventArgs
     {
         public IConfiguration Configuration { get; set; }
+        public User ProjectOwner { get; set; }
+        public Project Project { get; set; }
 
         public ProjectEventArgs(IConfiguration configuration, object[] args) : base(args)
         {
             Configuration = configuration;
         }
+
+        public ProjectEventArgs(IConfiguration configuration) : this(configuration, new object[0])
+        {
+        }
     }
 }