This fixes a bug where shop owner accounts would not be created in certain cases e.g. when the owner had certain admin permissions or created the account for another player while having certain admin permissions.
This adds separate permissions for accessing, creating and destroying of shops.
It also adds a config entry to allow using of a shop even if someone have access to it due to their permissions.
This uses a cache for players that we haven't found before so to not check the cache too often and also checks if the online mode of the queried OfflinePlayer matches the server's mode (gotten from the first logged-in player in order to be compatible with BungeeCord requiring the server to be in offline-mode.
This changes events to store the database Account instead of an OfflinePlayer and deprecates any event method that uses/returns OfflinePlayer. This is necessary as Bukkit#getOfflinePlayer(String) queries Mojang for the UUID when the user was not found in the local cache. As we already store this information (name to UUID mapping) in our database we should not have no need to rely on querying Mojang. (This might make transactions fail for shop owners that haven't played before but that shouldn't really be an issue in most cases)
This should fix the issue where the player's short name on the shop sign does not reflect the actual player's name. This works by storing every uuid-username combination together with the associated short name and the last time the player logged in with that combination.
This should fix issues with how name changes are handled and also prevent short names of different players from clashing. It also uses guava caches instead of maps now with a configurable cache size
