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/command_mute_test.go

@@ -4,11 +4,12 @@
 package app
 
 import (
+	"testing"
+	"time"
+
 	"github.com/mattermost/mattermost-server/model"
 	"github.com/nicksnyder/go-i18n/i18n"
 	"github.com/stretchr/testify/assert"
-	"testing"
-	"time"
 )
 
 func TestMuteCommandNoChannel(t *testing.T) {