Support --verbose

[tlovett1]

It would be nice to have a --verbose flag that just spits out lots of info helpful for debugging.

[michael-sumner]

An undocumented feature (command flags) which recently helped another 10upper troubleshoot an issue with existing wp-cli package dependencies was to use --debug to identify the issue. It was noted that --help (or pre-existing knowledge with wp-cli flags) are other ways to identify the --debug flag exists.