Appending to log file (#229)

Changing to appending to the log file so logs will correctly rotate.  This prevents large amounts of null data at the start of a rotated log file.

echo-web/etc/init/echo.conf

@@ -9,4 +9,4 @@ expect fork
 
 stop on stopping spinnaker
 
-exec /opt/echo/bin/echo 2>&1 > /var/log/spinnaker/echo/echo.log &
+exec /opt/echo/bin/echo 2>&1 >> /var/log/spinnaker/echo/echo.log &