Update the message names for Config RPC. (#93)

* Update the message names for Config RPC.

* Update message order and name.

* Rename to UpdatedLibraryConfig.

* Update gen-go files.

opencensus/proto/agent/trace/v1/trace_service.proto

@@ -32,16 +32,16 @@ option go_package = "github.com/census-instrumentation/opencensus-proto/gen-go/a
 service TraceService {
   // After initialization, this RPC must be kept alive for the
   // entire life of the application. The agent pushes configs
-  // down to applications via a stream of requests.
-  rpc Config(stream ConfigTraceServiceResponse) returns (stream ConfigTraceServiceRequest) {}
+  // down to applications via a stream.
+  rpc Config(stream CurrentLibraryConfig) returns (stream UpdatedLibraryConfig) {}
 
   // Allows applications to send spans to the agent.
   // For performance reasons, it is recommended to keep this RPC
   // alive for the entire life of the application.
   rpc Export(stream ExportTraceServiceRequest) returns (stream ExportTraceServiceResponse) {}
 }
 
-message ConfigTraceServiceRequest {
+message CurrentLibraryConfig {
   // Identifier data effectively is a structured metadata.
   // This is required only in the first message on the stream.
   opencensus.proto.agent.common.v1.Node node = 1;
@@ -50,7 +50,7 @@ message ConfigTraceServiceRequest {
   opencensus.proto.trace.v1.TraceConfig config = 2;
 }
 
-message ConfigTraceServiceResponse {
+message UpdatedLibraryConfig {
   // Requested updated configuration.
   opencensus.proto.trace.v1.TraceConfig config = 2;
 }