[C+B] Created FusedExplosive interface. Adds BUKKIT-3962, BUKKIT-3905

There is currently no unified way to represent explosives with a fuse, and to get/set the fuse ticks.

The problem is addressed here by creating an interface just for that : FusedExplosive.

The interface FusedExplosive extends Explosive, and is used for all fused entities (TNTPrimed, TNTMinecart and Creeper). The implementation is given in the corresponding CB PR.

CB-1117 - https://github.com/Bukkit/CraftBukkit/pull/1117 - Implementation.

BUKKIT-3962 - https://bukkit.atlassian.net/browse/BUKKIT-3962
BUKKIT-3905 - https://bukkit.atlassian.net/browse/BUKKIT-3905