Cfd protocol got moved into a separate repository.
All references of `cfd_protocol` were renamed to `maia`.
Patch cargo.toml with a fixed git revision until it gets a public release.
Mockall is a mocking framework that removes the need for writing more actors,
making tests easier to write.
Summary:
- add one more layer of indirection (a trait per actor type: Wallet, Oracle, Monitor)
- Mocks implementing the actor traits (with default stubbed implementations if no extra
behaviour needed)
- references to the mocks are being passed into the tests (via Arc<Mutex>>), allowing
for dynamically changing the behaviour and adding assertions. This also
aids readability, as the mock setup can be collocated with a particular
test, if the test needs something extra
Fixes#450