JERSEY-1650: jersey-proxy-client contains no OSGi metadata

 - added maven-bundle-plugin to jersey-proxy-client to generate OSGi headers
 - created OSGi test for jersey-proxy-client (copied the one that was alredy present in the jersey-proxy-client module)

Change-Id: I15215a9db6f45dbd6cc191b92e2502af8d762ae4