[MNOE-137] Add Her middleware to handle errors

[ouranos]

Handle connection and server errors

Mnoe api call will now raise Faraday::Error::ConnectionFailed or Faraday::Error::ClientError instead of returning nil

When the call is valid but the resource is not found it'll still return nil to keep the same behavior.

[ouranos]

@alachaum FYI

[BrunoChauvet]

LGTM