sr: add http scheme to url only if it's missing
logging: adjust message format, <level>: <message>
hls: Error on live streams

This can be overriden using the --force flag, but the output may
be a bit disappointing --- only the current state of the HLS
playlist is downloaded, and no reload is attempted.
hds: Error on live streams

This can be overriden using the --force flag.
Reraise UIExceptions when called with --verbose