Better verbosity & support for Python yanked packages

Fixed

• Resolve versions for yanked Python packages for exact version matching and
  arbitrary equality #125
• Resolved pre-release versions only when --pre option is specified #126

Changed

• Verbosity level is defined by number of -v (or --verbose) options: errors only -v; info and errors -vv; debug, info and errors -vvv
• Fallback to GitHub API for license detection is visible for info verbosity level (#89)