Fixes GH-1389
Because we are no longer enabling creepers to rapidly change status
every tick, in order to prevent event spam, their datawatcher value
ends up negative.
This datawatcher value is used to increment the fuseTicks within the
creeper tick. Because the value is negative, it is constantly zero'd
and therefore never incremented, instead acting the same as creepers
that aren't ignited.
We can just as easily increment this ourselves when the creeper is
ignited, so that's what we'll do.
