Disable block place event simulation by default. Fixes #456+

Due to the dupe bugs it causes with several mods, disabling
the block placement event simulation by default for now. Fixes
duplicate item drops when placing Flan's Mod weapon boxes, and
likely others: #551, #438, #456.

If you see missed events as a result of this change, check
bukkit.yml for how to re-enable (globally or per-blockID), and:

MinecraftPortCentral/MCPC-Plus@17c753ad54c2ed248ce80735351ebb99112de4de