```
mc alias set
alias remove
alias list
```
are new commands that replace mc config host sub-commands.
mc config host will still be available but hidden for backward
compatiblity. The JSON output is also kept if the user is running mc
config host command.
--rewind will go back in time and select specific object versions that are
the latest at the specified time.
--versions will display all the versions
cp will just ignore if the latest version is a delete marker
ls will print delete markers with a (deleted) at the end
This commit adds a new global context, monitors os signals
and cancels the global context in such cases to exit
on going process gracefully.
It will also update minio-go and adapts the code with
the new context changes in the admin API.
