added placeholder for categories list
Merge branch 'master' of https://github.com/pratz/cmsplugin-zinnia into feature/category-plugin
Update the code to use ZinniaCMSPluginBase
Rename CMSCategoriesPlugin to CMSPublishedCategoriesPlugin
Simplify the logic of the CMSPublishedCategoriesPlugin
Use a more explicit template name
Merge branch 'feature/category-plugin' into develop