Marshalling multierror

[malpiatko]

Hey,

I am using your multierror package in my project however I need to wrap it and add a MarshalJSON as it doesn't Marshal out of the box (because of the Func field). Would it be ok to add it to your project? In my case it would just marshal the error array. I don't know if you would want to do something more elaborate

[mitchellh]

Sounds good to me. I commented on your PR, if we can unmarshal then I think its fine!

[malpiatko]

I changed the code and answered your suggestions :)

[ConradIrwin]

@mitchellh Another attempt here: #15

The problem I was trying to solve was just that it fails, but adding a round-trip does seem kind of handy, so done.