Removed superfluous recalculation call; Fixes BUKKIT-3728

The permission attachment interface provides two methods each for setting
and unsetting permissions. Each one also provides an extra call to the
recalculatePermissions() method on the permissible, which degrades
performance.

This commit removes the duplicate call to recalculate permissions.
Spigot POM Changes.
Measure the duration of the entire timings run.
Improved Timings System

Enables "Timings on Demand" so you can enable/disable timings without server restart.
Tracks timings on sync events a plugin registers (Single and Repeating)
Tracks how many ticks a timed area has caused the server to lose due to taking too long.
Enables automatically pasting to paste.ubuntu.com so you can quickly review the results on aikar.co/timings.php
Add nag for bad plugins.
PlayerItemDamageEvent