Implement particles

I added SpongeParticle as implementation of Particle. As particles are enum in vanilla, I think this is only way to do that, although it is pretty ugly.

I also added setParticles() to SpongeGameRegistry. It does exactly same as setItemTypes(), but with particles.

Edit: See https://github.com/SpongePowered/SpongeAPI/pull/260
Enums will throw an `IllegalArgumentException` if the name is not available, so this would always return an available type or throw an exception, never `Optional.absent()`.