Spotifywebapipython

* Added `SpotifyDiscovery.DiscoveredResults` class property that will contain an array of `ZeroconfDiscoveryResult` items that contain discovery details for each service that was discovered.
* Added model `ZeroconfDiscoveryResult` class that contains detailed Zeroconf ServiceInfo details that were discovered via Zeroconf.
* Added model `ZeroconfProperty` class that contains Zeroconf ServiceInfo property details that were discovered via Zeroconf.
* Added model `ZeroconfResponse` class that contains Zeroconf basic response variables.
* Added model `ZeroconfGetInfo` class that contains Zeroconf action=getInfo response variables.
* Added model `ZeroconfGetInfoAlias` class that contains Zeroconf action=getInfo Alias response variables.
* Added model `ZeroconfGetInfoDrmMediaFormat` class that contains Zeroconf action=getInfo DRM Media format response variables.
* Added logic to handle `503 Server Error` responses from the Spotify Web API.
* Added support for Spotify DJ playlist retrieval. As the Spotify Web API does not support retrieving the DJ playlist (`spotify:playlist:37i9dQZF1EYkqdzj48dyYq`), it simply returns a manually built representation of the playlist. Note that playlist tracks cannot be retrieved either for the DJ playlist, as the Spotify Web API does not support it.

* Added device name support to the following player methods that take a `deviceId` argument for player functions. You can now specify either a device id or device name in the `deviceId` argument to target a specific Spotify Connect Player device. `SpotifyClient` methods updated were: `AddPlayerQueueItem`, `PlayerMediaPause`, `PlayerMediaPlayContext`, `PlayerMediaPlayTrackFavorites`, `PlayerMediaPlayTracks`, `PlayerMediaResume`, `PlayerMediaSeek`, `PlayerMediaSkipNext`, `PlayerMediaSkipPrevious`, `PlayerSetRepeatMode`, `PlayerSetShuffleMode`, `PlayerSetVolume`, `PlayerTransferPlayback`.
* Added `SpotifyClient.PlayerConvertDeviceNameToId` method that converts a Spotify Connect player device name to it's equivalent id value if the value is a device name. If the value is a device id, then the value is returned as-is.

* Added `Device.IsMuted` property to indicate if volume is zero (muted) or not (unmuted).
* Added `PlayerPlayState.IsMuted` property to indicate if player device volume is zero (muted) or not (unmuted).
* Updated `SpotifyClient.PlayerMediaPlayTrackFavorites` method to set the shuffle mode prior to starting play of the track list. Prior to this change, the first track would always play first regardless of the shuffle setting; now it is part of the shuffle.

* Added `ArtistInfo` model that contains artist bio information.
* Added `ArtistInfoTourEvent` model that contains artist on tour event information.
* Added `SpotifyClient.GetArtistInfo` method to retrieve artist bio information for a specified Artist id.
* Added `SpotifyClient.PlayerMediaPlayTrackFavorites` method to play all tracks contained in the current users track favorites.
* Added `SpotifyClient.RemovePlaylist` method to remove a playlist by calling the `UnfollowPlaylist` method.

* Updated `SpotifyClient.PlayerVerifyDeviceDefault` method to check for a null `Device.Id` value when determining if an active device was set.
* Added `delay` argument to various `SpotifyClient` player command-related methods, which allows the Spotify Web API a little bit of time to process the change before returning from the method. Methods updated: `PlayerMediaPause`, `PlayerMediaPlayContext`, `PlayerMediaPlayTracks`, `PlayerMediaResume`, `PlayerMediaSeek`, `PlayerMediaSkipNext`, `PlayerMediaSkipPrevious`, `PlayerSetRepeatMode`, `PlayerSetShuffleMode`, `PlayerSetVolume`, `PlayerTransferPlayback`, `PlayerVerifyDeviceDefault`. Default delay is 250 milliseconds, but you can adjust accordingly (including removing the delay if you wish).

* Updated `PlayerPlayState.__init__` model to properly parse the Actions property.