backport richtext behavior from Plone5 branch
Merge pull request #120 from plone/richtext-behavior

backport richtext behavior from Plone5 branch
Added condition on Archetypes warning viewlet to ensure the product will work for Dexterity only sites.
checkout plone.dexterity to use primary fields from behaviors
add utf-header
Since we now use the general RichText behavior, the test should write to that field, not the
specific IEventSummar richtext field. Refs #117
improve migration-results page
sort test to fix problem with test-isolation
Merge pull request #121 from plone/improve_migration_results_76

Improve migration results view (fix #76)
update Changes
Workon documentation and add more contributors
Merge master.