Adding support for "CommandHelp" attribute

Also changed "Output" and "Input" to be TextReader instead of string

Fix unit tests to work with new command descriptor semantics

--HG--
branch : dev
rename : src/Orchard/Commands/CommandManager.cs => src/Orchard/Commands/DefaultCommandManager.cs

src/Tools/Orchard/Host/CommandHost.cs

@@ -22,6 +22,8 @@ namespace Orchard.Host {
         public void RunCommand(OrchardParameters args) {
             var agent = Activator.CreateInstance("Orchard.Framework", "Orchard.Commands.CommandHostAgent").Unwrap();
             agent.GetType().GetMethod("RunSingleCommand").Invoke(agent, new object[] { 
+                Console.In,
+                Console.Out,
                 args.Tenant,
                 args.Arguments.ToArray(),
                 args.Switches});

src/Tools/Orchard/OrchardParametersParser.cs

@@ -20,7 +20,10 @@ namespace Orchard {
 
                     case "v":
                     case "verbose":
-                        result.Verbose = bool.Parse(sw.Value);
+                        bool verbose;
+                        if (!bool.TryParse(sw.Value, out verbose))
+                            verbose = true;
+                        result.Verbose = verbose;
                         break;
 
                     case "vp":