res_ari: Fix various memory leaks.

This change fixes a few memory leaks that were found based
on a mailing list post.

1. Some JSON response messages were never freed. This was
caused by the documentation stating that message references
were stolen when in reality they were not. The code now follows
the documentation and usage has been updated.

2. HTTP response headers were never freed.

3. The variable list for wildcards paths was never freed.

(closes issue ASTERISK-23128)
Reported by: Kenneth Watson (on list)

Review: https://reviewboard.asterisk.org/r/3119/
........

Merged revisions 405325 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@405326 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/ari.h

@@ -214,7 +214,7 @@ __attribute__((format(printf, 4, 5)));
  * \brief Fill in an \c OK (200) \a ast_ari_response.
  * \param response Response to fill in.
  * \param message JSON response.  This reference is stolen, so just \ref
- *                ast_json_incref if you need to keep a reference to it.
+ *                ast_json_ref if you need to keep a reference to it.
  */
 void ast_ari_response_ok(struct ast_ari_response *response,
 			     struct ast_json *message);
@@ -226,6 +226,10 @@ void ast_ari_response_no_content(struct ast_ari_response *response);
 
 /*!
  * \brief Fill in a <tt>Created</tt> (201) \a ast_ari_response.
+ * \param response Response to fill in.
+ * \param url URL to the created resource.
+ * \param message JSON response.  This reference is stolen, so just \ref
+ *                ast_json_ref if you need to keep a reference to it.
  */
 void ast_ari_response_created(struct ast_ari_response *response,
 	const char *url, struct ast_json *message);