Fixed tags_list response

[marcfowler]

The tags_list response doesn't contain the result_code, succeeded or success keys that are required for the response not to error out.

This PR handles responses that don't include those, in the same way that you handle ones that only respond with a string.

[mthommes]

Hi - thanks for letting us know about this. We have a pending change (#63) which should handle this in a slightly different manner. You'll be able to obtain the raw response, which just needs to be decoded.

Let us know of any questions! 😃

[ajimix]

@mthommes I guess if #63 is already merged, this PR can be closed then :)

[pevans]

Thanks, @ajimix!