Added /ghosthunter, /gh needs ghostplayer.player.beghosthunter : Normal players can see ghosts.
Added /removeghosthunter, /rgh <player> which needs ghostplayer.admin.removeghosthunter : Remove <player> from the ghost hunters.
Added new config option : GhostTime, now you can configure if you want to be a ghost only for a certain amount of time. (Time is in ticks, set to -1 if you don't want to use this option.)
New permissions : ghostplayer.player.*, ghostplayer.admin.*, ghostplayer.*.
