Update logger.js

if util.inspect.colors === undefined

/usr/local/lib/node_modules/Haraka/logger.js:43
    if (!util.inspect.colors[color]) return str;
                            ^
TypeError: Cannot read property 'blue' of undefined
    at colorize (/usr/local/lib/node_modules/Haraka/logger.js:43:29)

...
Merge pull request #632 from Illirgway/patch-1

Update logger.js