rhbz1124630 - remove client interfaces and most of the RESTEasy dependencies

We have to keep RESTEasy Multipart provider because we need to have those annotations on the Interface and DTO (missing them the server implementation will not work). When we package in fedora, we could make it a buildRequire dependency so RESTEasy won't be pulled in as runtime dependency.
We should be using GenericEntity instead. I haven't changed the server yet. It still depend on old API. I will test the server before merging this in.