json-rpc: don't try to set playcount/lastplayed for tvshows
json-rpc: fix resetting a datetime property through VideoLibrary.SetFooDetails
Merge pull request #4407 from Montellese/jsonrpc_fix_datetime_reset

JSON-RPC: fix resetting a datetime property through VideoLibrary.SetFooDetails
Merge remote-tracking branch 'upstream/Gotham'