Default value for min_sp_quality

[Janne Marie Moll]

The default value for min_sp_quality is reported to be 50, but in iggsearch.py line 84-85 it seems that the default value is set to 0:

species.add_argument('--min-sp-quality', type=int, default=0, metavar='INT', help="""Minimum quality score to report species (50)