bitcoin_cli as a global variable in the main __init__.py was creating issues related to http.client.CannotSendRequest: Request-sent and connection re-usage. Define a new connection per request.
The modules that need to run either bitcoind or the api do now reference to the fixture in the first test that needs it. Since the fixtures are definexd session-wise the rest of the modules will have access to them from that point on.
