added command /pokeballs buy, this command requires "pokeballs.buy" permission, the price of the pokeballs can be configured in the config.yml alongside the price of each 1% of successrate. example: a config like this:
pokeball price: 100.0
pokeball successrate pirce: 1.0
will cause a pokeball with a 100% successrate to cost 200.0$.

fixed a bug that would spam the player chat of players that dont have "pokeballs.use" permission.