* Add basic idea
* Implement the new logging strategy everywhere
* Remove unused const
* Add tests and fix error cases
* Fix logging in osquery service
* If there are extras, log info unless force debug
* Change to info
* Fix test
* Make logging context more chainable and force info for sessions
1. use [staticcheck](https://staticcheck.io/) to check the code, and fix some issues.
2. use `go fmt` to format the code.
3. use `go mod tidy` clean the go mod.
Notable refactoring:
- Use stdlib "context" in place of "golang.org/x/net/context"
- Go-kit no longer wraps errors, so we remove the unwrap in transport_error.go
- Use MakeHandler when setting up endpoint tests (fixes test bug caught during
this refactoring)
Closes#1411.
