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.

api4/api.go

@@ -4,11 +4,12 @@
 package api4
 
 import (
+	"fmt"
 	"net/http"
 
-	l4g "github.com/alecthomas/log4go"
 	"github.com/gorilla/mux"
 	"github.com/mattermost/mattermost-server/app"
+	"github.com/mattermost/mattermost-server/mlog"
 	"github.com/mattermost/mattermost-server/model"
 	"github.com/mattermost/mattermost-server/utils"
 
@@ -243,7 +244,7 @@ func Init(a *app.App, root *mux.Router, full bool) *API {
 func Handle404(w http.ResponseWriter, r *http.Request) {
 	err := model.NewAppError("Handle404", "api.context.404.app_error", nil, "", http.StatusNotFound)
 
-	l4g.Debug("%v: code=404 ip=%v", r.URL.Path, utils.GetIpAddress(r))
+	mlog.Debug(fmt.Sprintf("%v: code=404 ip=%v", r.URL.Path, utils.GetIpAddress(r)))
 
 	w.WriteHeader(err.StatusCode)
 	err.DetailedError = "There doesn't appear to be an api call for the url='" + r.URL.Path + "'."