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.

app/ratelimit.go

@@ -4,12 +4,13 @@
 package app
 
 import (
+	"fmt"
 	"math"
 	"net/http"
 	"strconv"
 	"strings"
 
-	l4g "github.com/alecthomas/log4go"
+	"github.com/mattermost/mattermost-server/mlog"
 	"github.com/mattermost/mattermost-server/model"
 	"github.com/mattermost/mattermost-server/utils"
 	"github.com/pkg/errors"
@@ -74,14 +75,14 @@ func (rl *RateLimiter) GenerateKey(r *http.Request) string {
 func (rl *RateLimiter) RateLimitWriter(key string, w http.ResponseWriter) bool {
 	limited, context, err := rl.throttledRateLimiter.RateLimit(key, 1)
 	if err != nil {
-		l4g.Critical("Internal server error when rate limiting. Rate Limiting broken. Error:" + err.Error())
+		mlog.Critical("Internal server error when rate limiting. Rate Limiting broken. Error:" + err.Error())
 		return false
 	}
 
 	setRateLimitHeaders(w, context)
 
 	if limited {
-		l4g.Error("Denied due to throttling settings code=429 key=%v", key)
+		mlog.Error(fmt.Sprintf("Denied due to throttling settings code=429 key=%v", key))
 		http.Error(w, "limit exceeded", 429)
 	}