MacDestroyer: Include fdesetup from 10.8 which allows the old behavior to work on 10.9/10.10.

Also rename postflight to postinstall and add a title to the Makefile
Update repo readme as Macdestroyer is not payload-only
fdesetup10.8 throws exceptions for status, list and remove. So use fdesetup for those, just use fdesetup10.8 for add
Use srm to remove input plist
Merge pull request #7 from russellhancox/master

Update macdestroyer for 10.9/10.10..