feat(rest): add GET execution method

- GET /execution/{id}

contributes to CAM-638
feat(rest): add signal execution method

- POST /execution/{id}/signal

contributes to CAM-638
feat(wink): support Apache Wink JAX-RS runtime

wink needs the Produces / Consumes annotation on method level

related to CAM-105
Merge branch 'master' of github.com:camunda/camunda-bpm-platform
fix(ExceptionHandler): add media type to exception handler

this will make sure the rest implementation knows which
MessageBodyWriter to pick

related to CAM-105
Merge remote-tracking branch 'upstream/master' into rest-api-additions