Sleep fixes

* __Fixed Lua errors when a sleeping player takes damage and has <=0 health.__
* __Fixed being able to bypass being frozen (FAdmin, ULX) with /sleep.__
* Fixed an issue where a sleeping player can respawn, after being killed, with less than 100 health.
* Fixed /sleep falsely being reported as disabled when you use /sleep while dead.
* Fixed the /sleep antispam notification not showing.
* Made the /sleep antispam notification more descriptive.