Encoding error during discussion hash compute

[gdchamal]

Need to take care of encoding in this part also

[mq-worker-697b466cf8-kn9v9] Traceback (most recent call last): 
[mq-worker-697b466cf8-kn9v9]   File "/srv/caliopen/src/backend/interfaces/NATS/py.client/caliopen_nats/subscribers.py", line 46, in process_raw 
[mq-worker-697b466cf8-kn9v9]     new_message = deliver.process_raw(payload['message_id']) 
[mq-worker-697b466cf8-kn9v9]   File "/srv/caliopen/src/backend/interfaces/NATS/py.client/caliopen_nats/delivery.py", line 36, in process_raw 
[mq-worker-697b466cf8-kn9v9]     message = self.qualifier.process_inbound(raw) 
[mq-worker-697b466cf8-kn9v9]   File "/srv/caliopen/src/backend/components/py.pi/caliopen_pi/qualifiers/mail.py", line 142, in process_inbound 
[mq-worker-697b466cf8-kn9v9]     new_message) 
[mq-worker-697b466cf8-kn9v9]   File "/srv/caliopen/src/backend/components/py.pi/caliopen_pi/qualifiers/mail.py", line 69, in lookup_discussion_sequence 
[mq-worker-697b466cf8-kn9v9]     seq.append(('hash', message.hash_participants)) 
[mq-worker-697b466cf8-kn9v9]   File "/srv/caliopen/src/backend/main/py.main/caliopen_main/message/parameters/message.py", line 62, in hash_participants 
[mq-worker-697b466cf8-kn9v9]     ids_hash = hash_participants_uri(self.participants) 
[mq-worker-697b466cf8-kn9v9]   File "/srv/caliopen/src/backend/main/py.main/caliopen_main/participant/core/participant.py", line 46, in hash_participants_uri 
[mq-worker-697b466cf8-kn9v9]     hash = hashlib.sha256(''.join(URIs)).hexdigest() 
[mq-worker-697b466cf8-kn9v9] UnicodeEncodeError: 'ascii' codec can't encode character u'\xef' in position 1587: ordinal not in range(128) 
[mq-worker-697b466cf8-kn9v9] ERROR:subscribers:deliver process failed for raw {u'message_id': u'a5ef57bd-08d1-45c7-b4e8-52cf679c6994', u'user_id': u'37005bef-1ed3-4511-9553-fb29d44d156e', u'order': u'process_raw', u'identity_id': u'a09d56d0-bfa0-408b-af39-0ed4d82fc4ef'}: None