Bug fixes and admin cancel command

This release brings GP back to it's latest version with a new modified Grief Prevention jar file.
Hopefully, by next release RealEstate will be able to work directly with the original Grief Prevention plugin, without need for a modified jar.

Changelog

New features

• /re cancel -- This command has been added for admins to be able to remove an existing transaction from the game

Bug fixes

• Added api version to plugin.yml
• Fixed a file creation error log
• Admins are now able to take parts into exit offers
• Subclaims for rent now don't inherit permissions from their parents, and the renter is now named manager from the claim until his rent expires. Owners need to be trusted explicitely by the renter to modify the subclaim
• Cleaned up old code