MolecEst/MolecLenEst.py: Fix tuple.append
MolecEst/MolecLenEst.py: Fix tuple.append

Fix the error:
AttributeError: 'tuple' object has no attribute 'append'

hackseq/2017_project_6,hackseq/2017_project_6,hackseq/2017_project_6,hackseq/2017_project_6