Nonce improvment (v4)

[alexcos20]

Right now, provider is using a fixed nonce (meaning all requests must have a nonce = provider_stored_nonce)
This is cumbersome, what endpoint are incrementing that and what endpoints do not ?
An additional enpoint call is needed, in order to get the nonce from provider, increasing bandwith usage & using provider workers

Solution:

• make nonce a float , so we can use timestamps with microseconds
• all calls requiring a nonce should check if the incoming nonce (specified in the request) is higher (and not equal to) then provider_stored_nonce. If yes, request is valid and provider_stored_nonce = new_received_nonce
• all clients (ocean.js/.py, market) can use timestamp (with microseconds) as nonce, thus not worrying about getting the last nonce
• keep getNonce endpoint, if client wants to build custom nonce tracking

Con:

• an address cannot have more then one call per microsecond, but we can live with that

[calina-c]

Closed by #279