GEOMESA 116 Ensuring backwards compatilibty with text encoding

For migrating from 0.10.x to 1.0.0 we need to default to text encoding for tables that already exist even if the user calls AccumuloDataStore.createSchema() with the featureEncoding set to FeatureEncoding.AVRO which is incorrect and would create problems when reading or writing data (because there'd be mixed serializations in a single feature store).