Better error handling

[internalsystemerror]

Feature Request

Q	A
New Feature	yes
RFC	no
BC Break	no

Summary

The GitHub API returns a response like {"message":"error message", "errors": ['error 1','error 2']} on error. We should utilise this field if available, falling back to the current generic error messages.

[Ocramius]

IMO we can perhaps consider raising the debug level of the tooling by default?

Currently, the LOG_LEVEL environment variable is undocumented, and set to INFO by default 🤔