Show a summary widget instead of the full blown environment model.

Hides the gory details, and in most cases the user doesn't care anyway.

src/plugins/cmakeprojectmanager/cmakebuildenvironmentwidget.cpp

@@ -38,7 +38,6 @@ bool debug = false;
 
 using namespace CMakeProjectManager;
 using namespace CMakeProjectManager::Internal;
-using ProjectExplorer::EnvironmentModel;
 
 CMakeBuildEnvironmentWidget::CMakeBuildEnvironmentWidget(CMakeProject *project)
     : BuildStepConfigWidget(), m_pro(project)