VCS: Offer to save-all before commit

Task-number: QTCREATORBUG-3857
Change-Id: I3ff3d90803eec4134b9da4af5567753ad7bffafb
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/git/gitplugin.cpp

@@ -926,6 +926,9 @@ void GitPlugin::gitGui()
 
 void GitPlugin::startCommit(CommitType commitType)
 {
+    if (!promptBeforeCommit())
+        return;
+
     if (raiseSubmitEditor())
         return;
     if (isCommitEditorOpen()) {