Fix for issue #67. Exposed the underlying Apache client in the constr…

…uctor.

src/main/java/org/kairosdb/client/HttpClient.java

@@ -106,13 +106,23 @@ public HttpClient(String url) throws MalformedURLException
 	public HttpClient(HttpClientBuilder builder, String url) throws MalformedURLException
 	{
 		checkNotNullOrEmpty(url, "url cannot be null");
-		checkNotNull(builder, "builder cannot be null");
+		checkNotNull(builder, "builder must not be null");
 		this.url = url;
 		new URL(url); // validate url
 		client = builder.build();
 		typeRegistry = new DataPointTypeRegistry();
 	}
 
+	public HttpClient(CloseableHttpClient client, String url) throws MalformedURLException
+	{
+		checkNotNullOrEmpty(url, "url cannot be null");
+		checkNotNull(client, "client must not be null");
+		this.url = url;
+		new URL(url); // validate url
+		this.client = client;
+		typeRegistry = new DataPointTypeRegistry();
+	}
+
 	public void registerCustomDataType(String groupType, Class dataPointClass)
 	{
 		checkNotNullOrEmpty(groupType, "groupType may not be null or empty");