Change how renderer output is converted to JSON

[malcolmbaig]

Context

• The 0.4.0 release has a bug which incorrectly serialises part of the document, returning arrays of over-escaped strings rather than arrays of JSON hashes in the data field.
• This bug was fixed in master.
• The fix introduced another bug which leads to inconsistencies in the output JSON. This PR attempts to fix that bug.

Changes proposed in this pull request

Update the railtie to fix issues with the way renderer output is converted into a JSON string in the controller.

Cached and non-cached resources need slightly different handling, so make a logical check to tell the difference and use the appropriate method.

[remear]

Thanks for this!

[phanle]

@remear Can we release a new version of the gem to have this commit?

[remear]

My intent was to first fix the CI to ensure a stable release, of which there's a PR up I need to go review, then get this shipped. Sadly, I haven't had as much time to work on this as I'd like. I'll try to wrangle some time to get this out soon.

[jkva]

Seconding this - I'm dealing with the same JSON serialisation double encoding problem since I've tried to add caching, would love to see this released 😁