StatsD: Write skeleton Asterisk application

Wrote the skeleton framework for the Asterisk StatsD dialplan
application. This includes a load function, unload function, a
callback for execution, and XML documentation.

ASTERISK-25419
Reported By: Ashley Sanders

Change-Id: I9597730e134c6e82c8a55ef4d5334b62dd473363

apps/app_statsd.c

+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2015, Digium, Inc.
+ *
+ * Tyler Cambron <tcambron@digium.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+ /*** MODULEINFO
+	<depend>res_statsd</depend>
+	<defaultenabled>no</defaultenabled>
+	<support_level>extended</support_level>
+ ***/
+
+#include "asterisk.h"
+
+ASTERISK_REGISTER_FILE()
+
+#include "asterisk/module.h"
+#include "asterisk/logger.h"
+
+/*** DOCUMENTATION
+	<application name="Statsd" language="en_US">
+		<synopsis>
+			Allow statistics to be passed to the StatsD server from the dialplan.
+		</synopsis>
+		<syntax>
+			<parameter name="metric_type" required="true">
+				<para>The metric type to be sent to StatsD.</para>
+			</parameter>
+			<parameter name="statistic_name" required="true">
+				<para>The name of the variable to be sent to StatsD.</para>
+			</parameter>
+			<parameter name="value" required="true">
+				<para>The value of the variable to be sent to StatsD.</para>
+			</parameter>
+		</syntax>
+		<description>
+			<para>This dialplan application sends statistics to the StatsD server
+			specified inside of <literal>statsd.conf</literal>.</para>
+		</description>
+	</application>
+ ***/
+
+static const char app[] = "Statsd";
+
+static int statsd_exec(struct ast_channel *chan, const char *data)
+{
+	ast_log(LOG_NOTICE, "StatsD application callback is working!\n");
+	return 0;
+}
+
+
+static int unload_module(void)
+{
+	return ast_unregister_application(app);
+}
+
+static int load_module(void)
+{
+	return ast_register_application_xml(app, statsd_exec);
+}
+
+AST_MODULE_INFO_STANDARD_EXTENDED(ASTERISK_GPL_KEY, "Statsd Dialplan Application");
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