Fix treatment of slashes and add tests (#28)

MyriadPlugin.Test/HttpClient.fs

@@ -0,0 +1,17 @@
+namespace MyriadPlugin.Test
+
+open System.Net.Http
+
+/// Simple implementation of an HttpClient.
+type HttpClientMock (result : HttpRequestMessage -> Async<HttpResponseMessage>) =
+    inherit HttpClient ()
+
+    override this.SendAsync (message, ct) =
+        Async.StartAsTask (result message, cancellationToken = ct)
+
+[<RequireQualifiedAccess>]
+module HttpClientMock =
+    let make (baseUrl : System.Uri) (handler : HttpRequestMessage -> Async<HttpResponseMessage>) =
+        let result = new HttpClientMock (handler)
+        result.BaseAddress <- baseUrl
+        result