Structured logging (#8673)

* Implementing structured logging

* Changes to en.json to allow refactor to run.

* Fixing global logger

* Structured logger initalization.

* Add caller.

* Do some log redirection.

* Auto refactor

* Cleaning up l4g reference and removing dependancy.

* Removing junk.

* Copyright headers.

* Fixing tests

* Revert "Changes to en.json to allow refactor to run."

This reverts commit fd8249e99bcad0231e6ea65cd77c32aae9a54026.

* Fixing some auto refactor strangeness and typo.

* Making keys more human readable.

store/sqlstore/command_webhook_store.go

@@ -7,8 +7,7 @@ import (
 	"database/sql"
 	"net/http"
 
-	l4g "github.com/alecthomas/log4go"
-
+	"github.com/mattermost/mattermost-server/mlog"
 	"github.com/mattermost/mattermost-server/model"
 	"github.com/mattermost/mattermost-server/store"
 )
@@ -86,9 +85,9 @@ func (s SqlCommandWebhookStore) TryUse(id string, limit int) store.StoreChannel
 }
 
 func (s SqlCommandWebhookStore) Cleanup() {
-	l4g.Debug("Cleaning up command webhook store.")
+	mlog.Debug("Cleaning up command webhook store.")
 	exptime := model.GetMillis() - model.COMMAND_WEBHOOK_LIFETIME
 	if _, err := s.GetMaster().Exec("DELETE FROM CommandWebhooks WHERE CreateAt < :ExpTime", map[string]interface{}{"ExpTime": exptime}); err != nil {
-		l4g.Error("Unable to cleanup command webhook store.")
+		mlog.Error("Unable to cleanup command webhook store.")
 	}
 }