Add a CLI

[postmodern]

Add a ronin-sql CLI.

• Add the ronin-core dependency for the command_kit gem.
• Add bin/ronin-sql executable file.
• Add Ronin::SQL::CLI module/namespace.
• Add the command_kit/completion/task rake task to the Rakefile.
• Add a man/ronin-sql.1.md file and the kramdown/man/task rake task to the Rakefile to generate the man pages.
• Add the generated_files list to the gemspec.yml and add the man/ronin-sql*.1 and data/completions/ronin-sql files.
• Add a Synopsis section to the README.