File cache sync via curl (#2851)

* Add sendevent when using file caching

* Create clear_cache.lua

FS receives a command via curl to call this script which deletes the single cache entry or flushes the entire cache.

* Create file_cache.lua

This scripts monitors for custom events. When an event is processed it will send out a command via curl to other FS servers telling them to clear their cache. 

This must be called from conf/autoload_configs/lua.conf.xml
 <param name="startup-script" value="app/server/resources/memcache.lua"/>

resources/install/scripts/app/servers/resources/clear_cache.lua

@@ -0,0 +1,37 @@
+--includes
+	require "resources.functions.config";
+	local Database = require "resources.functions.database";
+	local Settings = require "resources.functions.lazy_settings"
+	dbh = Database.new('system');
+	local settings = Settings.new(dbh, domain_name, domain_uuid);
+	
+	
+--define trim
+	function trim (s)
+		return (string.gsub(s, "^%s*(.-)%s*$", "%1"))
+	end
+	
+--get the argv values
+	cmd = argv[1];
+	file = argv[2];
+
+--get the cache directory
+	local cache_dir = settings:get('cache', 'location', 'text')
+
+	if (cmd ~= nil) then
+		cmd = trim(cmd);
+		freeswitch.consoleLog("NOTICE","api_command: "..cmd .. " cache\n");
+	end
+	
+	if (cmd == "flush") then
+		os.execute("rm " .. cache_dir .. "/*");
+	end
+	
+	if (cmd == "delete") then
+		if (file ~= nil) then
+			file = trim(file);
+			freeswitch.consoleLog("NOTICE","api_command: delete ".. cache_dir .. "/" .. file .. "\n");
+			os.remove(cache_dir.."/"..file);
+		end
+	
+	end