Re-booking jaegertracing/jaeger#586

The UI must url-encode service name when calling the API to retrieve operation names: /api/services/{service}/operations. It does some encoding, but not correctly, e.g.

• one of our internal services is emitting a bad service name ${artifactId}, and the API request looked like this /api/services/$%7BartifactId%7D/operations, which is ok
• however, when the service name contains a slash like hotrod/customer, the slash is not encoded correctly: http://localhost:16686/api/services/hotrod/customer/operations

Incidentally, the API supports an alternative endpoint /api/operations?service={service}, we should decide which one we want to keep.