RavenDB-4286 increased timeout to prevent task canceled exception fro…

…m throwing, this could occur on slow machines when database is being loaded for a first time

Raven.Tests.Web/Tests/WebTestBase.cs

@@ -26,7 +26,7 @@ protected WebTestBase()
         {
             client = new HttpClient
                      {
-                         Timeout = TimeSpan.FromSeconds(10)
+                         Timeout = TimeSpan.FromSeconds(20)
                      };
         }