return object if mapped as create_entity does
extent recognizing of already existing objects

organization: /has already been taken/
user: /already exists/
host-collection: /must be unique within one organization/
product: Product with name '<name>' already exists in this organization
repository: /has already been taken for this product./
content-view: /has already been taken/
activation-key: /has already been taken/
template-snippet: /has already been taken/
catch exceptions when deleting system content views
add template snippet import to simple test