Allow Guilds to set Tax Rate

With Garrison being remove and no sign of cash flow coming back, give guild the option to enable and set the tax rate for the guild, preferably for each ranking. The tax will move a percentage of the members gold to the guild bank to help struggling guilds survive. If guild do not want to use it then they can keep it disable. This will allow guilds struggling financially to be able to give back to the community through guild repair and rewards.