Switch to Java 8, some compiler tweaks
Switch to Java 8, some compiler tweaks

Optimized the shade plugin. Might break some plugin dependencies, maybe. Shrinks file size a lot.

Switched to Java 8 because Sponge does it and it is just common sense to use the latest version.

BlazePowered/Blaze-Server,jimmikaelkael/GlowstonePlusPlus,GlowstoneMC/GlowstonePlusPlus,GlowstonePlusPlus/GlowstonePlusPlus,GlowstoneMC/GlowstonePlusPlus,GreenBeard/GlowstonePlusPlus,GlowstonePlusPlus/GlowstonePlusPlus,LukBukkit/GlowstonePlusPlus,GlowstonePlusPlus/GlowstonePlusPlus,BlazePowered/Blaze-Server,GreenBeard/GlowstonePlusPlus,BlazePowered/Blaze-Server,jimmikaelkael/GlowstonePlusPlus,GreenBeard/GlowstonePlusPlus,jimmikaelkael/GlowstonePlusPlus,GlowstoneMC/GlowstonePlusPlus,LukBukkit/GlowstonePlusPlus,GlowstonePlusPlus/GlowstonePlusPlus,BlazePowered/Blaze-Server,LukBukkit/GlowstonePlusPlus,LukBukkit/GlowstonePlusPlus,GreenBeard/GlowstonePlusPlus,GlowstoneMC/GlowstonePlusPlus,jimmikaelkael/GlowstonePlusPlus