Correctly set version info when building, fixed build script and added headers for apps endpoints.

internal/configuration/config.go

@@ -27,6 +27,8 @@ type Config struct {
 		// Endpoint is a remote application endpoint which should give us metrics
 		// in Prometheus format.
 		Endpoint string
+		// Headers is a list of headers that should be added to metrics request.
+		Headers map[string]string
 		// TimeBetweenRequests is a minimal amount of time which should pass
 		// between requests.
 		TimeBetweenRequests time.Duration