Comma separating multiple placeholders

when passed into oFtFormsPlaceholderOptionalSelector
fixing a few more cases of the same error
Update radio button styles to match latest Origami designs
Use tick icon for check-boxes
Merge branch 'master' into fixing-multiple-placeholders

* master:
  Change section border colour ref to palette rather than user case ref
  Move fieldset/form sections to it own partial and adjust margin, padding and borders as requested by design
  embolden error message text and clear extraneous comments from global errors
  Revert form error messaging to red text without block background.
  Fixed scss-lint errors. Update o-colors version. Set colour use cases for error-global. Updated demo config format. Re-built demos.
  Updated to latest version o-fonts. Use oFontsGetFontFamilyWithFallbacks() function. Updated origami.json demo format.
  Simplify markup for radio buttons and checkboxes
  Remove grids dependency from demos (except prefixes/suffixes; to be fixed separately)

Conflicts:
	src/scss/field-errors.scss
	src/scss/prefix-suffix.scss
Add comments and fix placeholder names
Merge pull request #31 from Financial-Times/update-radio-checkbox-styles

Update radio checkbox styles
Get rid of the white-space rule and ensure checkbox tick is always placed within checkbox

This is to deal with multi-line labels
Merge pull request #37 from Financial-Times/fix-checkboxes

Get rid of the white-space rule and ensure checkbox tick is always place...
Merge pull request #19 from Financial-Times/fixing-multiple-placeholders

Comma separating multiple placeholders
Merge branch 'master' of https://github.com/Financial-Times/o-ft-forms into fix-prefixes-suffixes

Conflicts:
	src/scss/prefix-suffix.scss