Bosesoundtouchapi

* Updated Recently Played List cache logic to set the SourceTitle value for recently played items.

* Updated Recently Played List cache logic to convert Spotify tracklisturl references to uri references. If the playing content is a context (e.g. artist, playlist, album, etc), then the context info is in the NowPlayingStatus contentItem data and the TRACK info is in the individual fields. Failure to do this results in duplicate items in the cache with just the contentItem Name field different.

* Added Recently Played List cache processing. This allows a cache of recently played content items to be stored on the local file system. WebSocket support must be enabled for the caching to work, as it utilizes the nowPlayingUpdated event to drive played content to the cache.
* Updated `Recent` model with setter properties so that a recent item could be created without xml.

* Removed `xmltodict` requirement.
* Added method `ContentItem.ToDictionary` to return a dictionary representation of the class.
* Added method `MediaItemContainer.ToDictionary` to return a dictionary representation of the class.
* Added method `NavigateItem.ToDictionary` to return a dictionary representation of the class.
* Updated `NavigateResponse.ToDictionary` method to remove the xmltodict requirement.
* Added method `Preset.ToDictionary` to return a dictionary representation of the class.
* Updated `PresetList.ToDictionary` method to remove the xmltodict requirement.
* Added method `Recent.ToDictionary` to return a dictionary representation of the class.
* Updated `RecentList.ToDictionary` method to remove the xmltodict requirement.
* Updated `SearchResponse.ToDictionary` method to remove the xmltodict requirement.
* Added method `SearchResult.ToDictionary` to return a dictionary representation of the class.
* Updated `SearchStationArtists.ToDictionary` method to remove the xmltodict requirement.
* Added method `SearchStationResults.ToDictionary` to return a dictionary representation of the class.
* Updated `SearchStationSongs.ToDictionary` method to remove the xmltodict requirement.
* Added method `SourceItem.ToDictionary` to return a dictionary representation of the class.
* Updated `SourceList.ToDictionary` method to remove the xmltodict requirement.

* Updated `NowPlayingStatus.ContainerArtUrl` property to return the correct image url of the playing content: the `ArtUrl` value is returned if present; otheriwse the `ContentItem.ContainerArt` url is returned if present; otherwise, None is returned. Prior to this fix, the `ContentItem.ContainerArt` value was considered first which did not always match the `ArtUrl` value and thus caused an incorrect image to be displayed for the currently playing artist and track value.

* Added `NowPlayingStatus.ContainerArtUrl` property to return the `ContentItem.ContainerArt` url if present; otherwise, the `ArtUrl` value is returned.