add note about needing require json for JRUBY < 1.7.0
add note about needing require json for JRUBY < 1.7.0

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