Improve PLEX connector
Improve PLEX connector

Add support for 'remote' UI located on https://app.plex.tv/web.

Closes #954.
Closes #1378.

Paszt/web-scrobbler,fakelbst/Chrome-Last.fm-Scrobbler,inverse/web-scrobbler,alexesprit/web-scrobbler,david-sabata/web-scrobbler,galeksandrp/web-scrobbler,fakelbst/Chrome-Last.fm-Scrobbler,david-sabata/web-scrobbler,carpet-berlin/web-scrobbler,alexesprit/web-scrobbler,galeksandrp/web-scrobbler,carpet-berlin/web-scrobbler,Paszt/web-scrobbler,inverse/web-scrobbler