Caches the MetaImage for the Article
Fixes a small bug in caching the ArticleImage
Caches another MetaImage object
Caches the ArticleImageIndex
Caches the ArticleImagesList
Bug
Bugfixes
Caches the MetaImage
Caches the has_image in the MetaArticle
Caches the hasAttachment() result in the MetaArticle and the ArticleAttachmentsList
Bugfixes
Clears the cache for the Attachment CacheKey
Merge branch 'CS-5413' of https://github.com/terwey/Newscoop

Conflicts:
	newscoop/template_engine/classes/ArticleImagesList.php
	newscoop/template_engine/metaclasses/MetaArticle.php
	newscoop/template_engine/metaclasses/MetaImage.php
Merge branch 'master' of github.com:sourcefabric/Newscoop