Add post not finished.
Write about quick edit feature.
Text improvements.
Fix some sample code and write about tests.
Add conclusion.
Fix post date.
Merge branch 'gh-pages' into post/quick-add-and-quick-edit-on-active-admin
Update post date.
Merge pull request #185 from Helabs/post/quick-add-and-quick-edit-on-active-admin

Add blog post: "Quick add and quick edit on active admin"