Initialize AtExitManager before calling MainApplicationBundlePath

Some singleton calsses require the existence of AtExitManager.

atom/app/atom_library_main.mm

@@ -6,6 +6,7 @@
 
 #include "atom/app/atom_main_delegate.h"
 #include "atom/app/node_main.h"
+#include "base/at_exit.h"
 #include "base/i18n/icu_util.h"
 #include "base/mac/bundle_locations.h"
 #include "brightray/common/mac/main_application_bundle.h"
@@ -21,6 +22,7 @@ int AtomMain(int argc, const char* argv[]) {
 }
 
 int AtomInitializeICUandStartNode(int argc, char *argv[]) {
+  base::AtExitManager atexit_manager;
   base::mac::SetOverrideFrameworkBundlePath(
       brightray::MainApplicationBundlePath()
           .Append("Contents")