Revert "Class name is enough - no need for complete package path!"

This reverts commit c893644a1a91e1fb29cbf21147e6d851a29077ae.
Revert "Warn about missing configuration properties"

This reverts commit 94d24ff0ce050653cc85b063ed7ba72154b3674c.
Fix compatibility with CraftBukkit but warn about missing properties.

Of course only on Spigot and BungeeCord..
Revert "Revert "Class name is enough - no need for complete package path!""

This reverts commit 15cabf4b996e10cf511c0ec744000c46b92aaabb.