Implement HandleEpisodeAction

[TheBlusky]

I figured out GET /api/2/episodes/(username).json was not implemented.

I had to add relvacode/iso8601 dependencie in order to parse the since argument (time.RFC3339 is not compatible)

Hope I did everything the way you would have done it :-)

[TheBlusky]

After using this branch on dalily basis, there is a bug with antenna pud trying to retrieve episodes.

(It sends since=0 which isn't an iso8601 date format. I'll work on that. In the mean time, don't merge it yet :-)

[oxtyped]

Thanks for working on this! 🙇

[gilcu3]

@TheBlusky is there any progress on this? As far I can see the only thing missing is a corner case in the timestamp parsing? I can help if necessary.

@oxtyped Can devices currently synchronize episode actions without this PR? Sorry if it is a silly question.