Add createWallet method

[tiero]

It seems is not exported yet. There is a way to do a raw rpc call with this library, like in this case?

[pedrobranco]

You can use client.command method to call RPC methods. Example:

client.command('createwallet', 'foobar', true)
  .then(response => console.log(response));
// Outputs: { name: 'foobar', warning: '' }

[pedrobranco]

Now you can use directly the method createWallet on the latest version v2.2.0.