SPIGOT-485: Special case TnT in explosions.

I tested this in the original commit, maybe IDE didn't recompile properly.

nms-patches/Explosion.patch

@@ -1,5 +1,5 @@
---- ../work/decompile-8eb82bde/net/minecraft/server/Explosion.java	2015-01-25 10:44:43.764182684 +1100
-+++ src/main/java/net/minecraft/server/Explosion.java	2015-01-25 10:44:43.768182687 +1100
+--- ../work/decompile-8eb82bde/net/minecraft/server/Explosion.java	2015-01-28 08:50:50.364126925 +1100
++++ src/main/java/net/minecraft/server/Explosion.java	2015-01-28 08:50:50.368126914 +1100
 @@ -8,6 +8,12 @@
  import java.util.List;
  import java.util.Map;
@@ -60,7 +60,7 @@
 +                        CraftEventFactory.entityDamage = source;
 +                        boolean wasDamaged = entity.damageEntity(DamageSource.explosion(this), (float) ((int) ((d13 * d13 + d13) / 2.0D * 8.0D * (double) f3 + 1.0D)));
 +                        CraftEventFactory.entityDamage = null;
-+                        if (!wasDamaged) {
++                        if (!wasDamaged && !(entity instanceof EntityTNTPrimed)) {
 +                            continue;
 +                        }
 +                        // CraftBukkit end