Remove replication of code to get current host #264
Description
The code to fetch the current host URL is repeated in these two places:
- https://github.com/Cloud-CV/evalai-cli/blob/master/evalai/set_host.py#L14
- https://github.com/Cloud-CV/evalai-cli/blob/master/evalai/utils/auth.py#L88-L100
The util method get_host_url can be used in the host command instead.