Fahrenheit Conversion Inconsistencies

[mag2352]

I understand that this is a hacky way of resolving the StopIteration problems, but this resolves the issue I have in #72. Unless someone can dedicate significant time into determining how the conversion process differs, this is enough to allow HomeAssistant to function as expected with the Gree units that I have, and this PR should not cause any issues for those who don't have these problems.