Big fix about /ultimatelevels set command which was working bad with use-vault set to false, and a small fix on the same command which showed the message "Player not found" after changing a player's level even if the change was successfull

Fixed an error which appeared when a server didn't have PlaceholderAPI installed.

Now you can insert all the world names where "/levels" should not work.
In addition to this, the plugin supports now PlaceholderAPI:
%ultimatelevels_level% - Get player's level
%ultimatelevels_nextlevel% - Get next player's level

P.S: Remove the config folder and restart the server to add the new values, or add them manually (you can see the config.yml in the overview page). This is the first and last time I ask this because of a fix I've added in this version about config

Thank you!