Add HD Wallet integration (temporary and hacky!!!)

Add RPC/Websocket calls for:

getdepositscript
createseries
replaceseries
thawseries
The point is about unit testing as much as possible, and using integration tests for the rest. We do that because unit tests are usually cheaper to write, much faster to run and always more robust. When doing TDD, you'll usually end up with most of your code unit-testable, but since we're not yet doing that, It's a common practice to refactor your code into constructs that can be unit-testable so that you end up with as little as possible code with no unit tests. In this specific case we'd be able to unit test most of the new code by calling the functions that take just a Manager, and then we'd only need integration tests to check that the "createseries" & co operations are exposed on the websocket interface.