Generate models

[darrelmiller]

AB#8499

[baywet]

basic model support previously added
inline schema & collection support added by #38

TODO:

• allOf: inheritance
• oneOf: using a wrapper class where there is a property for each of types in the oneOf. Only one of the properties should be non-null
• anyOf: For AnyOf we use the same wrapper class and allow any of the properties to be non-null.

This would work similar to the way you are doing collections with "MessagesResponse".

[baywet]

oneOf and anyOf should actually be a type union (translated to a backward compatible wrapper class for languages that don't support that feature)