Base64 encoding in HTTP Auth modules requires Python3 Unicode string handling

[justb4]

Describe the bug
Base64 encoding requires proper Python3 string handling

To Reproduce
Steps to reproduce the behavior, e.g.:

1. Configure a stetl.inputs.HttpInput with Basic Auth
2. Running it
3. Expected to see successful
4. Seeing error : something like TypeError: expected bytes-like object, not str

Expected Behavior
No error.

Screenshots or Logfiles
This is a left-over from the Python2 to Python3 migration: need to use Unicode Strings in Python3.
Many examples like https://stackoverflow.com/questions/53340627/typeerror-expected-bytes-like-object-not-str

Context (please complete one or more from the following information):

• OS: any
• Python Version: 3.7
• Stetl Version 2.1
• Stetl Input/Output/Filter Component: stetl.inputs.HttpInput and stetl.outputs.HttpOutput (maybe more)
• Stetl Config file NA

If running with Docker:

• Docker installed version
• Stetl Docker Image version: 2.1

Additional context
Current version stetl.inputs.HttpInput.

    def add_authorization(self, request):
        """
        Add authorization from config data. Authorization scheme-specific.
        May be extended or overloaded for additional schemes.

        :param request: the HTTP Request
        :return:
        """
        auth_creds = self.auth
        auth_type = auth_creds['type']
        auth_val = None
        if auth_type == 'basic':
            # Basic auth: http://mozgovipc.blogspot.nl/2012/06/python-http-basic-authentication-with.html
            # base64 encode username and password
            # write the Authorization header like: 'Basic base64encode(username + ':' + password)
            auth_val = base64.encodestring('%s:%s' % (auth_creds['user'], auth_creds['password']))
            auth_val = "Basic %s" % auth_val
        elif auth_type == 'token':
            # Bearer Type, see eg. https://tools.ietf.org/html/rfc6750
            auth_val = "%s %s" % (auth_creds['keyword'], auth_creds['token'])

        request.add_header("Authorization", auth_val.replace('\n', ''))

must become something like:

    def add_authorization(self, request):
        """
        Add authorization from config data. Authorization scheme-specific.
        May be extended or overloaded for additional schemes.

        :param request: the HTTP Request
        :return:
        """
        auth_creds = self.auth
        auth_type = auth_creds['type']
        auth_val = None
        if auth_type == 'basic':
            # Basic auth: http://mozgovipc.blogspot.nl/2012/06/python-http-basic-authentication-with.html
            # base64 encode username and password
            # write the Authorization header like: 'Basic base64encode(username + ':' + password)
            auth_val = base64.encodebytes(
                '{}:{}'.format(auth_creds['user'], auth_creds['password']).encode())
            auth_val = 'Basic {}'.format(auth_val.decode())
        elif auth_type == 'token':
            # Bearer Type, see eg. https://tools.ietf.org/html/rfc6750
            auth_val = "%s %s" % (auth_creds['keyword'], auth_creds['token'])

        request.add_header("Authorization", auth_val.replace('\n', ''))