Support path expansion in config file

Support configuration path such as "%APPDATA%\blah" which are expanded
when read in

Rhino.ServiceBus.Tests/ConfigReaderTests.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Threading;
+using Castle.MicroKernel.Registration;
+using Castle.Windsor;
+using Castle.Windsor.Configuration.Interpreters;
+using Rhino.ServiceBus.Impl;
+using Rhino.ServiceBus.Internal;
+using Rhino.ServiceBus.Config;
+using System.IO;
+using Xunit;
+
+namespace Rhino.ServiceBus.Tests
+{
+    public class ConfigReaderTests
+    {
+
+        [Fact]
+        public void Can_get_path_variable()
+        {
+            var bus = new BusElement();
+            var expected = @"folder\app\one_way";
+            bus.Path = @"folder\app";
+
+            Assert.Equal(expected+".esent", bus.QueuePath);
+            Assert.Equal(expected + "_subscriptions.esent", bus.SubscriptionPath);
+        }
+
+        [Fact]
+        public void Can_get_path_variable_replacement()
+        {
+            var bus = new BusElement();
+            var expected = Path.Combine(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "app"), "one_way");
+            bus.Path = @"%APPDATA%\app";
+
+            Assert.Equal(expected+".esent", bus.QueuePath);
+            Assert.Equal(expected + "_subscriptions.esent", bus.SubscriptionPath);
+        }
+    }
+}