Include the analyzer in the token_count datatype serialized json

Fixes #1744

Author: russcam

src/Nest/Mapping/Types/Specialized/TokenCount/TokenCountProperty.cs

@@ -5,6 +5,7 @@ namespace Nest
 	[JsonObject(MemberSerialization.OptIn)]
 	public interface ITokenCountProperty : INumberProperty
 	{
+        [JsonProperty("analyzer")]
 		string Analyzer { get; set; }
 	}
 

src/Tests/ClientConcepts/HighLevel/Mapping/AutoMap.doc.cs

@@ -468,6 +468,10 @@ public void OverridingAutoMappedAttributes()
 										.Name("firstNameRaw")
 										.Index(FieldIndexOption.NotAnalyzed)
 									)
+                                    .TokenCount(t => t
+                                        .Name("length")
+                                        .Analyzer("standard")
+                                    )
 								)
 							)
 							.Number(n => n
@@ -554,8 +558,13 @@ public void OverridingAutoMappedAttributes()
 									{
 										index = "not_analyzed",
 										type = "string"
-									}
-								},
+									},
+                                    length = new
+                                    {
+                                        type = "token_count",
+                                        analyzer = "standard"
+                                    },
+                                },
 								type = "string"
 							},
 							isManager = new