Index installed sounds and implement ARI sounds queries

This adds support for stasis/sounds and stasis/sounds/{ID} queries via
the Asterisk RESTful Interface (ARI, formerly Stasis-HTTP).

The following changes have been made to accomplish this:
* A modular indexer was created for local media.
* A new function to get an ast_format associated with a file extension
  was added.  
* Modifications were made to the built-in HTTP server so that URI
  decoding could be deferred to the URI handler when necessary.
* The Stasis-HTTP sounds JSON documentation was modified to handle
  cases where multiple languages are installed in different formats.
* Register and Unregister events for formats were added to the system
  topic.

(closes issue ASTERISK-21584)
(closes issue ASTERISK-21585)
Review: https://reviewboard.asterisk.org/r/2507/


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@392700 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/sounds_index.h

@@ -0,0 +1,55 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2013, Digium, Inc.
+ *
+ * Kinsey Moore <kmoore@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.
+ */
+
+/*! \file
+ * \brief Sound file format and description indexer.
+ */
+
+#ifndef _ASTERISK_SOUNDS_INDEX_H
+#define _ASTERISK_SOUNDS_INDEX_H
+
+#if defined(__cplusplus) || defined(c_plusplus)
+extern "C" {
+#endif
+
+/*!
+ * \brief Object representing a media index
+ */
+struct ast_media_index;
+
+/*!
+ * \brief Reload the sounds index
+ *
+ * \retval zero on success
+ * \retval non-zero on failure
+ */
+int ast_sounds_reindex(void);
+
+/*!
+ * \brief Get the sounds index
+ *
+ * \retval sounds index (must be ao2_cleanup()'ed)
+ * \retval NULL on failure
+ */
+struct ast_media_index *ast_sounds_get_index(void);
+
+#if defined(__cplusplus) || defined(c_plusplus)
+}
+#endif
+
+#endif /* _ASTERISK_SOUNDS_INDEX_H */