Merge pull request JohnnyCrazy#135 from henningms/master

JohnnyCrazy#134 Adds User-Agent in the OAuth request due to recent changes in th…

Added new endpoint "recently played"

Made some LocalAPI methods async - Updated example, now without Synch…

…ronizingObject

Cleanup HTTPServer and more stuff

Fixed wrong visibility in BasicModel

Fixed Tests with adding ResponseInfo.Empty

Added alternative way to get the next page

GetAlbumArtUrl() fix

Fixed GetAlbumArtUrl

Updated Newtonsoft.Json to 8.0.2