Rendered Help doesn't show default value for Options

[robertjpayne]

This is marked as a TODO in the source, willing to submit a PR do we want it rendered just as:

--<name> - <description> (Default: <default>)

Flags should also probably be updated to --[no-]<name> - <description> (Default: false)

[kylef]

@robertjpayne A PR here would be very welcome.