Git: Modernize

* pragma once
* member initialization
* s/struct/class/
* Introduce a static GitPlugin::client() method and use it

Change-Id: Ifdcac86dd16f3cdba11d564d03e9a15f00a6afdb
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/git/gitutils.cpp

@@ -25,20 +25,12 @@
 
 #include "gitutils.h"
 
-#include <QDebug>
 #include <QInputDialog>
 #include <QLineEdit>
 
 namespace Git {
 namespace Internal {
 
-QDebug operator<<(QDebug d, const Stash &s)
-{
-    QDebug nospace = d.nospace();
-    nospace << "name=" << s.name << " branch=" << s.branch << " message=" << s.message;
-    return d;
-}
-
 void Stash::clear()
 {
     name.clear();