Bug fixes

• Adds more detailed error messages with links for troubleshooting them
• Prevent deleting sub content of linked directories
• Allows printing optional head tags in embedded content
• Updated CKEditor to version 4.7.3
• Added Greek translations (thanks to xarhsdev)
• Added Finnish translations (thanks to Janne Särkelä)
• Added support for editor iframe reloading
• Allow multiple content to be loaded at the same time
• A complete re-write of the hub-client and major improvements to it's error messages

Fixed required version of Core and Editor in composer.json.
Fixed proper clearing of cache when a library/content type is updated.
Fixed old libraries always updating.
Adds more detailed error messages with links for troubleshooting them.
Prevent deleting sub-content of linked directories.
Updated CKEditor to version 4.7.3.
Added Greek translations (thanks to xarhsdev).
Added Finnish translations (thanks to Janne Särkelä).
Added support for editor iframe reloading.
Allow multiple content to be loaded at the same time.