Added administration.lua.

Adds self-hosted, single-realm administrative functions to otouto.
Check out the README for a detailed description.

Also added msg.from.name, which is msg.from.first_name + msg.from.last_name (if it
exists), because I'm too lazy to build it each time.
Fixed a crash-causing bug (ironically) in the handle_exception() function.

utilities.lua

@@ -148,6 +148,8 @@ end
 
 handle_exception = function(err, message)
 
+	if not err then err = '' end
+
 	local output = '\n[' .. os.date('%F %T', os.time()) .. ']\n' .. bot.username .. ': ' .. err .. '\n' .. message .. '\n'
 
 	if config.log_chat then