refactored the welcome plugin to use a web api instead of a hard coded file

removed deprecated file class
don't wait for response when setting dvar/sending command in T6
potential fix for duplicate kick message in JS plugin

SharedLibraryCore/Server.cs

@@ -321,7 +321,6 @@ namespace SharedLibraryCore
         protected int ConnectionErrors;
         protected List<string> BroadcastMessages;
         protected TimeSpan LastMessage;
-        protected IFile LogFile;
         protected DateTime LastPoll;
         protected ManualResetEventSlim OnRemoteCommandResponse;