Added `/balance` and `/pay` commands and a config option to enable them.
Added safeIs method to Config to match values without case sensitivity.
Added getCurrencyText method to Config to generate a formatted string from a currency amount.
Value 'format' from config file now supports amount-name replacement.
Main now stores the instance of VaultLayer for further use.
Rewrite of config loading to support automatic missing field writing, reloading.
Economy item Material is now provided by Config.
Ender Chest support can now be disabled, `getInventory` (renamed to `getInventoryList`, the old method now returns an instance of Inventory) now returns an empty Inventory instance if Ender Chest is disabled.
