Special display for API vs. CLI command help

The help text returned from the server used to just contain API-specific
examples. To facilitate CLI-specific examples, the help format is now
decomposed into pieces: "summary", "description", etc. This change displays
the pieces of the help, defaulting to showing CLI examples. API examples
can still be shown via the new `--api`/`-a` flag. The priority for what to
display is now this:
- Decomposed help + CLI examples
- Decomposed help + API examples (must have `--api`/`-a` flag)
- Unified help (included for backwards compatibility)

Fixes https://tickets.puppetlabs.com/browse/RAZOR-272