NRedisSearch: don't throw for everyone who doesn't have the module

TODO: inherit from tests project and use a proper Skip.

NRediSearch.Test/ExampleUsage.cs

@@ -36,7 +36,23 @@ public void BasicUsage()
                 .AddTextField("body", 1.0)
                 .AddNumericField("price");
 
-            Assert.True(client.CreateIndex(sc, Client.IndexOptions.Default));
+            bool result = false;
+            try
+            {
+                result = client.CreateIndex(sc, Client.IndexOptions.Default);
+            }
+            catch (RedisServerException ex)
+            {
+                // TODO: Convert to Skip
+                if (ex.Message == "ERR unknown command 'FT.CREATE'")
+                {
+                    Console.WriteLine(ex.Message);
+                    Console.WriteLine("Module not installed, aborting");
+                    return; // the module isn't installed
+                }
+            }
+
+            Assert.True(result);
 
             // note: using java API equivalent here; it would be nice to
             // use meta-programming / reflection instead in .NET