* Rewritting to java
- rewritten a lot of Spring Cloud Contract Spec module to Java
- extracted all Groovy stuff to a separate package
- will now continue writing extension modules
- spring-cloud-contract-spec will be written purely in java
- spring-cloud-contract-spec-groovy will have Groovy extensions
fixes gh-1130
with this change we're adding generation of 2 docker images - verifier and stub runner
we also added a project `spring-cloud-contract-stub-runner-boot` which contains a far jar with stub runner boot
fixes gh-526, gh-516