Support more IANA json codes

[paolosimone]

@RVFET review

[...] For example: rdap.nominet.uk/uk/domain/domain.uk will not be formatted even though the response is json

In fact document.contentType: 'application/rdap+json' was not supported. Now the extension should be enabled for all json media types.

Will be available with version 1.1.2

[RVFET]

8Thank you so much for taking my request into account. Would be great if the extension could fallback to trying to parse the response into json even when content type does not match any json format, just as a last chance, it'd be a great addition.

Edit: I'm aware that it'd create some performance bottlenecks since it'd need to check every page you visit but it could be an option that we can toggle, or perhaps manual wildcard/regex based custom websige matching could help a ton, too.

[paolosimone]

moved the discussion here #50