3.1.4

• Don't modify params passed into Address#create (#78; thanks Dmitry Ishkov (@TheRusskiy))
• Don't modify carriers and services parameters to Shipment.lowest_rate (#71 / #103, thanks Vladimir Vinnikov (@vladvinnikov) and Juris Galang (@jurisgalang))
• When constructing an easypost object, convert the key to a string (#102; thanks Geesu (@Geesu))
• Expose the raw HTTP response as #http_body on EasyPost::Error objects (#101; thanks Geesu (@Geesu))