Add parsing out stdout from trim-low-abund.py
Add parsing out stdout from trim-low-abund.py

Explicitly check that the output of trim-low-abund can be parsed as
FASTA when it is being redirected to stdout.

souravsingh/khmer,souravsingh/khmer,ged-lab/khmer,ged-lab/khmer,souravsingh/khmer,ged-lab/khmer