* Add viper (for env variable) support to CLI
* Move the "featurebase cli" sub-command to its own "fbsql" command
I don't know if this is the final name, but putting it here as a
placeholder for now.
* Handle single `--command` flags.
This also adds a printer interface so we can opt NOT to print setup
information in non-interactive mode.
* Add support for multiple `--command` flags in the same call
* Add support for multiple `--file` flags
* Move members related to Config into a separate struct
* Make sure non-interactive mode can connect to a database
* comment fix
* support control-C on readline
* Prevent connection message from printing in non-interactive mode
* Return errors (instead of printing them) in non-interactive mode