Render Documents with their Locale

When a page is rendered currently the site locale and in some use cases the user's locale is used. The former is intended, the latter is a bug.

We should allow to render documents, especially their properties with the locale used in the document (projectdoc.doctype.common.locale). This would allow larger instances to use different locales for different pages.

We need to check if the Blueprint API allows us to define the locale. In previous versions this was not possible,