Merge pull request #13 from jianglai/flushing

Log metric flusing error at warning level

Author: jianglai

metrics/src/main/java/com/google/monitoring/metrics/MetricExporter.java

@@ -64,7 +64,7 @@ protected void run() throws Exception {
           writer.flush();
         } catch (IOException exception) {
           logger.log(
-              Level.SEVERE, "Threw an exception while writing or flushing metrics", exception);
+              Level.WARNING, "Threw an exception while writing or flushing metrics", exception);
         }
       } else {
         logger.info("Received a poison pill, stopping now");