separate the model, rest and domain to three modules in the light-rest-4j-generator

[stevehu]

The benefits:

The model jar can be used by the consumer independently.
The rest module will be generated based on the specification.
The business logic will be in the domain module and it won't be overwritten if exists.

[stevehu]

separate the model, rest and domain to three modules in the light-rest-4j-generator light-codegen master