Fix for issue AER-3447.
Fix for issue AER-3447.

Now, all UTF-8 string values stored in DB including record keys will
be returned to the user in UTF-8 string format and not Unicode string.

trupty/aerospike-client-python,aerospike/aerospike-client-python,aerospike/aerospike-client-python,trupty/aerospike-client-python,trupty/aerospike-client-python,arthurprs/aerospike-client-python,arthurprs/aerospike-client-python,aerospike/aerospike-client-python,arthurprs/aerospike-client-python