Sample ID's matching the same id in the reference cluster files are not assigned into heirarchy

[jrober84]

If the user supplies a set of query samples B,C into an existing set of clusters A,B,C,D, they will be assigned new cluster codes all the way through as they will be treated as too distant to assign due to a skip on line 188 in assign.py

            if q_id in self.memberships_dict:
                continue

options for solving.

1. Check for containment of the same sample id's in the query as in the clusters and fail if true. User needs to remove them.

2. Allow for shadowing of sample_id's in the data and still perform the assignment.