Initial Integration tests for HTTP / IPC servers

[njgheorghita]

From https://github.com/carver/trin/pull/2#issuecomment-791053427

A natural follow-up will be to figure out a way to do integration tests on the http and ipc servers. Maybe we can hit only the clientVersion endpoint for now, though we'll obviously want to test Infura endpoints eventually. Also, we'll probably want arbitrary backing URLs. That's important soon, so we don't hit Infura for real during tests, and later so we can support any type of endpoint (like alchemyapi.io).