Update Args class serialisation process with byte arrays

[ASAPSegfault]

Context
As of testnet 17, parameters sent to smart contract are now byte arrays and not strings anymore
The args class serialise data into a string, it needs to be updated to match the new standard.

How to

• The Args class must serialise data in byte arrays instead of strings
• The Args class must deserialise data from a byte array instead of a string

Technical details:

• To be added

[Thykof]

I think it's already solved by #39

[ASAPSegfault]

Indeed it looks like so. Closing the issue.