GEOMESA-191 Implement deleteSchema for featureType

deleteSchema removes both metadata and the 3 tables per feature type. Also
checks to see whether or not it's an older 0.10.x table, and if so, uses
the AccumuloFeatureWriter's remove() function to remove rows from the table.
deleteSchema() should actually only delete the rows from 0.10.x tables, and then this test checks that table again for the existence of those rows...so the table would still exist. I can delete the table as well though if that's the behavior we want.