Fix UnicodeEncodeError with --write-info-json on Python 2.7 + Windows

Fixes #4244
Fix "ERROR: Cannot write metadata to JSON file" on Windows

Fixes #4246
Merge pull request #4247 from ivan/info-json

Fix #4246 and #4244 .info.json bugs
release 2014.11.20
Remove binary and auto-updating entry point
Remove update functionality
Update UA
Wait ~1 sec between HTTP requests to avoid getting CAPTCHAed by Google
For YouTube videos we already have, skip without even requesting video info
When continuing a YouTube download with --continue, skip it if the directory has any download with the same ID, even if it has a different filename.
Copy the mtime from the oldest source file to the file created by ffmpeg

Fixes #4245
Use os.replace when available to avoid intermittent FileExistsError problems