Add a comand line editor for environment variables

Task-number: QTCREATORBUG-6499

Change-Id: I43df7bddd10776e0fdb192c668ab0d99a6fea7e6
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>
Reviewed-by: hjk <qthjk@ovi.com>

src/libs/utils/environmentmodel.cpp

@@ -366,6 +366,7 @@ void EnvironmentModel::setUserChanges(QList<Utils::EnvironmentItem> list)
     d->m_items = list;
     d->updateResultEnvironment();
     endResetModel();
+    emit userChangesChanged();
 }
 
 } // namespace Utils