Init.
Exception caught at 324: 'NoneType' object is not iterable
Traceback (most recent call last):
  File "/usr/bin/logster", line 319, in main
    submit_stats(parser, duration, outputs)
  File "/usr/bin/logster", line 216, in submit_stats
    output.submit(metrics)
  File "/usr/lib/python2.6/site-packages/logster/outputs/graphite.py", line 45, in submit
    for metric in metrics:
TypeError: 'NoneType' object is not iterable