There were a lot of instances of this lint error
printf: non-constant format string in call to github.com/rclone/rclone/fs.Logf (govet)
Which were fixed by re-arranging the arguments and adding "%s".
There were quite a few genuine bugs which were found too.
- add context to log and fallthrough to error log level
- test: use rclone random lib to generate random strings
- calculate hash from vfs cache if file is uploading
- add server started log with server url
- remove md5 hasher
