Single, universal function for printing outputs

[tdviet]

The outputs are printed by every command separately. It would be easier for maintaining to have a single place for printing output.

The function print_output(output_data, format, delimiter, template_string) where output_data could be a dict or list of dicts, and format could be table, csv, JSON, YAML, env (format for environment variables), value (values only), template (see #167). When printing in csv format, the user can define custom delimiter, e.g. tab instead of comma. More formats could be added easily as we have all printing in single place.