Add rivine Create and Open wallet convenience methods

[robvanmieghem]

No description provided.

[ahussein]

Can you please add more information to the ticket describing what is the purpose of these new methods and how they will be used by client code.

[robvanmieghem]

The documentation currently states how to create a wallet

 client_data = {'bc_address': 'https://explorer.testnet.threefoldtoken.com/',
'password_': 'test123',
 'minerfee': 10,
 'nr_keys_per_seed': 5,
 'seed_': seed}

    rivine_client = j.clients.rivine.get('mytestwallet', data=client_data)
    rivine_client.config.save()

or

wallet = RivineWallet(seed=seed,
                                   bc_network='https://explorer.testnet.threefoldtoken.com/',
                                   bc_network_password='test123',
                                   nr_keys_per_seed=5,
                                   minerfee=100000000)

I would like a create wallet that creates and saves it directly, an open wallet method would initiate it based on the saved information

[ahussein]

merged to development_simple