add answer work tag to httapi

src/mod/applications/mod_httapi/docs/mod_httapi_doc.txt

@@ -230,6 +230,12 @@ action		    : Change url to submit to.
 temp-action	    : Change url to submit to. just for the next loop.
 
 
+<answer is-conference>
+		    : Answer the call
+
+ATTRS:
+is-conference       : true|false (set the conference flag for RFC4579 stuff.
+
 
 <hangup cause action>
 		    : Hangup the call

src/mod/applications/mod_httapi/mod_httapi.c

@@ -877,6 +877,19 @@ static switch_status_t parse_hangup(const char *tag_name, client_t *client, swit
 	return SWITCH_STATUS_FALSE;
 }
 
+static switch_status_t parse_answer(const char *tag_name, client_t *client, switch_xml_t tag, const char *body)
+{
+	const char *conf = switch_xml_attr(tag, "is-conference");
+
+	if (conf && switch_true(conf)) {
+		switch_channel_set_flag(client->channel, CF_CONFERENCE);
+	}
+
+	switch_channel_answer(client->channel);
+
+	return SWITCH_STATUS_FALSE;
+}
+
 static switch_status_t parse_record_call(const char *tag_name, client_t *client, switch_xml_t tag, const char *body)
 {
 	const char *limit_ = switch_xml_attr(tag, "limit");
@@ -2997,6 +3010,7 @@ SWITCH_MODULE_LOAD_FUNCTION(mod_httapi_load)
 	bind_parser("sms", parse_sms);
 	bind_parser("dial", parse_dial);
 	bind_parser("pause", parse_playback);
+	bind_parser("answer", parse_answer);
 	bind_parser("hangup", parse_hangup);
 	bind_parser("record", parse_record);
 	bind_parser("recordCall", parse_record_call);