Fixed: effects not removed when a player quits as a spectator.

I use the `disableSpectate` method, instead of re-doing (partially, that was the cause of the bug) the stuff needed to disable the spectator mode.

Branch name: `kickFix` because I thought this was a kick-related bug.

[Build here](http://jenkins.carrade.eu/job/SpectatorPlus-AmauryCarrade/3/artifact/SpectatorPlus/target/SpectatorPlus-B2.0.jar).