sketch of how properties should look like
introduce a schema root to hold the resources
fix design
introduce dsl, take some of the things from Resource out
Resource doesn't know about the sinatra app any longer!
definition takes attributes on initializer
change how definitions are set a bit
move dsl to new module
extract dsl for definitions into a new file
spec for definitions dsl
add links dsl
allow properties on links
fix resource properties
cosmetics
keep a full definition reference in properties
pass full properties for validation
allow referencing definitions
design update