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.
[picky] If this table is meant to represent the pre-secondary-index table, we might want to label it as such.