Disable RSpec warnings.

The dependency on rails-api is causing a number of RSpec warnings to be
generated when running the test suite. As these are not dangerous and
can only be changed by submitting PRs to the rails-api project itself
I’m disabling warnings for the time being.
Generate boilerplate Note model.

Initial Note model has two attributes: title & body. The password
attribute will be added at a later date once the basic functionality of
creating a note without one is delivered.