Fix javadoc publish (#1393)
Fix javadoc publish (#1393)

* Travis can't find gh-pages; this should fix that.

* Publish javadoc ONLY after an actual release

openzipkin/zipkin,adriancole/zipkin,twitter/zipkin,twitter/zipkin,openzipkin/zipkin,adriancole/zipkin,openzipkin/zipkin,twitter/zipkin,openzipkin/zipkin,openzipkin/zipkin,adriancole/zipkin,twitter/zipkin,adriancole/zipkin