base64 encodes a Powershell script and executes the powershell
        encoded script command

def run_ps(self, script):
        """base64 encodes a Powershell script and executes the powershell
        encoded script command
        """
        # must use utf16 little endian on windows
        encoded_ps = b64encode(script.encode('utf_16_le')).decode('ascii')
        rs = self.run_cmd('powershell -encodedcommand {0}'.format(encoded_ps))
        if len(rs.std_err):
            # if there was an error message, clean it it up and make it human
            # readable
            rs.std_err = self._clean_error_msg(rs.std_err)
        return rs