Move to "github.com/hashicorp/go-hclog" (#4227)

* logbridge with hclog and identical output

* Initial search & replace

This compiles, but there is a fair amount of TODO
and commented out code, especially around the
plugin logclient/logserver code.

* strip logbridge

* fix majority of tests

* update logxi aliases

* WIP fixing tests

* more test fixes

* Update test to hclog

* Fix format

* Rename hclog -> log

* WIP making hclog and logxi love each other

* update logger_test.go

* clean up merged comments

* Replace RawLogger interface with a Logger

* Add some logger names

* Replace Trace with Debug

* update builtin logical logging patterns

* Fix build errors

* More log updates

* update log approach in command and builtin

* More log updates

* update helper, http, and logical directories

* Update loggers

* Log updates

* Update logging

* Update logging

* Update logging

* Update logging

* update logging in physical

* prefixing and lowercase

* Update logging

* Move phyisical logging name to server command

* Fix som tests

* address jims feedback so far

* incorporate brians feedback so far

* strip comments

* move vault.go to logging package

* update Debug to Trace

* Update go-plugin deps

* Update logging based on review comments

* Updates from review

* Unvendor logxi

* Remove null_logger.go

logical/plugin/serve.go

@@ -4,7 +4,7 @@ import (
 	"crypto/tls"
 	"os"
 
-	hclog "github.com/hashicorp/go-hclog"
+	log "github.com/hashicorp/go-hclog"
 	"github.com/hashicorp/go-plugin"
 	"github.com/hashicorp/vault/helper/pluginutil"
 	"github.com/hashicorp/vault/logical"
@@ -19,7 +19,7 @@ type TLSProviderFunc func() (*tls.Config, error)
 type ServeOpts struct {
 	BackendFactoryFunc logical.Factory
 	TLSProviderFunc    TLSProviderFunc
-	Logger             hclog.Logger
+	Logger             log.Logger
 }
 
 // Serve is a helper function used to serve a backend plugin. This
@@ -27,8 +27,8 @@ type ServeOpts struct {
 func Serve(opts *ServeOpts) error {
 	logger := opts.Logger
 	if logger == nil {
-		logger = hclog.New(&hclog.LoggerOptions{
-			Level:      hclog.Trace,
+		logger = log.New(&log.LoggerOptions{
+			Level:      log.Trace,
 			Output:     os.Stderr,
 			JSONFormat: true,
 		})