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.

utils/file_backend_local.go

@@ -9,8 +9,7 @@ import (
 	"os"
 	"path/filepath"
 
-	l4g "github.com/alecthomas/log4go"
-
+	"github.com/mattermost/mattermost-server/mlog"
 	"github.com/mattermost/mattermost-server/model"
 )
 
@@ -28,7 +27,7 @@ func (b *LocalFileBackend) TestConnection() *model.AppError {
 		return model.NewAppError("TestFileConnection", "Don't have permissions to write to local path specified or other error.", nil, err.Error(), http.StatusInternalServerError)
 	}
 	os.Remove(filepath.Join(b.directory, TEST_FILE_PATH))
-	l4g.Info("Able to write files to local storage.")
+	mlog.Info("Able to write files to local storage.")
 	return nil
 }