* add --host and --kubeconf to `fx up`
* remove `fx infra list` and `fx infra use`
* put assets into skip dir for golangci
* fix lint issue
* upgrade go-ssh-client to consume the 'Connectable' API, enable more
friendly SSH connection error message
* parse 'host' and 'kubeconf' for `fx list` and `fx down` also
* refactor parse
* clean infra stuff