Listing Delays & Configuration Revamp

Added
+ Added delays between listings. Can be disabled by setting to 0 in "config.yml". Bypass permission "auctionhouse.delay.bypass"
+ Added "cooldown.yml" to the database folder to save cooldowns.

Removed
- None

Edited
- Recoded "config.yml" file to have a structure like "message.yml"
- Beautified and added detail to when the plugin is loading

Bugs Squashed
- Fixed a ConcurrentModificationException occurring when expiring listings