Comma separating multiple placeholders

when passed into oFtFormsPlaceholderOptionalSelector
fixing a few more cases of the same error
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
Merge pull request #19 from Financial-Times/fixing-multiple-placeholders

Comma separating multiple placeholders