WSS: Run ffmpeg.exe for image extraction as impersonation user for network drives

When the source files are on a network drive, we need to run ffmpeg.exe as a user with
access to that network drive.

Thanks to Shukuyen for endless debugging on this issue.
MPTVSeries: Read fanart images from Fanart table
MAS: Fix error message when query throws an error
Configurator: Do not crash when activity fails to load streams

Not doing anything is always better than crashing.
Merge branch 'release-0.5'

Conflicts:
	Services/MPExtended.Services.StreamingService/Code/Images.cs