Money.add_rate spec should not impact default_bank
Money.add_rate spec should not impact default_bank

* Otherwise other specs that do not expect a EUR -> USD rate
* to exist may get unexpected behavior

insphire/money,maicoin/money,bonusly/money,nilbus/money,printercu/money,BrandyMint/money,saizai/money,AlexVPopov/money,RubyMoney/money,richardvenneman/money,kewaunited/money,antstorm/money,gregoryhappyfresh/money,envato/money,paulodiniz/money