Unicode type is Py2 only

[iyesin]

fixes exception like:

name 'unicode' is not defined: NameError
Traceback (most recent call last):
  File "/var/task/Submitter.py", line 40, in handler
    producer.send(name.encode(encoding='ascii'))
  File "/var/task/kinesis_producer/producer.py", line 45, in send
    if isinstance(record, unicode):
NameError: name 'unicode' is not defined

while using python3