Also use the check command_name to store in series

[gst]

As explained between us and confirmed by influxdb people :
we should also use the check_command in the serie names we use to store the check metrics results.

So the serie name scheme becomes :
"metric_%s_%s" % (command_name, metric_name)

[gst]

Needed Shinken change : https://github.com/gst/shinken/tree/enh_also_give_check_command_in_broks