Rename o-ft-forms-field-group, section and global error messages classes to comply with BEM
Add border radius to section and global error message
Update the demo templates with BME compliant classes.
Clean up demo comments. Move inline demos into their own templates to be added to the demo config.json once styles have been defined.
Clean up global and section message colour refrences.
Merge pull request #39 from Financial-Times/fix-classnames

Fix classnames to be BEM compliant