add a json5 parser

[johanlelan]

I would like to be flexible on submitted JSON in request body. (allowing some mistakes)
To do this, i would like to use the JSON5 parser instead of JSON one. I looked for an option to add external parsers but it seems that it does not exist.
What do you think about this new feature?

[dougwilson]

Hi! This is a great suggestion and something we are tracking under #22

[dougwilson]

Hi! This is a good idea, but we really don't want to keep pulling in more and more dependencies. We should really put the effort towards implementing #22 which would make implementing this in user-land or even as an add-on module trivial.