Mode 1969 - Extended the standard JCR types with an additional SIMPLE_REFERENCE type.

Simple references behave like weak references the only major difference being that they do not cause back-pointers to be stored in the referring nodes. Because of this, they do not _show up_ when using the traditional JCR ```node.getReferences(..)``` methods.

The query system was updated as well to make sure that these kind of references are returned when using the ```REFERENCE``` operand. Also, while working on this I discovered & fixed a bug that prevented STRONG references from ever being located via this operand.