ckeditor content type validation for pictures and some tweaks.
Merge branch 'ckeditor' into dev

Conflicts:
	config/tinymce.yml
ckeditor assets precompilation added for production env
ckeditor assets precompilation  removed from production env
meta-tags gem. summary attribute to article model, site meta tag to application layout and  title, keywords, description meta tags to home page and article show page added.
Merge branch 'dev'