Fix BodyAsFile to also allow relative paths (#244)

* Read only .json files as static mapping files and fix current folder for BodyAsFile

* include .json again

* LocalFileSystemHandler_ReadResponseBodyAsFile_Throws

* Read array from static mappings folder

* xml soap example

src/WireMock.Net/Server/FluentMockServer.cs

@@ -203,6 +203,7 @@ namespace WireMock.Server
                 Urls = new[] { $"{(settings.UseSSL == true ? "https" : "http")}://localhost:{port}" };
             }
 
+            _options.FileSystemHandler = settings.FileSystemHandler;
             _options.PreWireMockMiddlewareInit = settings.PreWireMockMiddlewareInit;
             _options.PostWireMockMiddlewareInit = settings.PostWireMockMiddlewareInit;
             _options.Logger = _logger;