start extracting schem athings into a new class
cosmetics
moar cosmetics
extract class
separate tests
extract json schema dump of resources
extract json schema dump of definitions
extract json schema dump of links
support for datetime type
fix json schema dumping for date-time fields
cast datetime fields
lazily resolve references

the existing implementation only works when you can define a
property before referencing it. this is obviously not ideal for
more complex schemas, when you don't quite have the control about
the order properties are defined, or have circular dependencies