Fix: Update optionator, --no in help (fixes #1134)

- Updated optionator to 0.5.0
Boolean options with 'default: true' now display their negated variant
in help. eg. --no-eslintrc, --no-ignore, --no-color
- Updated help messages work with that eg. 'disable' rather than
  'enable'
- Removed 'default: false' from a couple of Boolean options - not
  needed, it's false(y) by default
- Added 'colour' as alias to 'color', to not be as American centric
- Updated command line interface docs with new help output
- Rearrange docs to be in the same order as the help output
- Fixed various formatting issues with the docs
- Added option 'color' to docs, was missing before
Well, every command line program I've used so far has a flag off unless specified otherwise, so I think it makes sense to leave it out. It's even more clear now that we have the "--no" variant displayed in the help for the other options.