Added ShieldBlockEvent

This should be posted after a successful shield block, allowing other mods a chance to perform special actions upon blocking
Posted ShieldBlockEvent from shieldHook method

- may need to import class
Fixes issue #75: IArrowCatcher not catching arrows
Merge pull request #72 from coolAlias/master

Event on successful shield block - Fix IArrowCatcher not catching arrows
Merge remote-tracking branch 'upstream/master'