Restructured some code and added a new permission blueshop.help,
if a player runs a blueshop command and doesn't have permission or the command fails,
it would show a list of command, not it'll only do that if the user has this permission.

If you're having issues with sign shops not working for non-opped players, change your
spawn-protection=16
to 0 in your server.properties file, just make sure another plugin like worldguard is protecting your spawn.
otherwise use "/gamerule spawnradius 0" in-game to change it per world.