Printing of primitive wrapper objects

[brigand]

new String(), etc. should be handled specially. Current behavior:

> var oi = require('object-inspect');
undefined
> oi(new Number(5))
'{}'
> oi(new String('hello'))
'{ 0: \'h\', 1: \'e\', 2: \'l\', 3: \'l\', 4: \'o\' }'
> oi(new Boolean(true))
'{}'

cc @ljharb