Fix error introduced with a past commit in client_daemon.
Now we use the same implementation of md5 calculation and correct TYPO error in modify request.
Add 'md5' in test of upload and modify method into test_connection_manager
Changed the creation of temporary file to use tempfile lib and removed debugging print.
Replaced io with tempfile lib to all the test about put and post files/.
The io.BytesIo doesn't have namefile attribute and this create problem with app.test_client() function of Flask.
Added new test with bad md5 in post and put files/.

Added some assert to ensure no modification or insertion into USERDATA dictionary and files when the md5 is different from the received md5 (file corrupted).