fix action bar select on tablet

On tablet, select an action item cause app to crash due to drawerToggle is null:
05-12 04:02:41.387  30327-30327/com.donnfelker.android.bootstrap.debug E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.NullPointerException
            at com.donnfelker.android.bootstrap.ui.NavigationDrawerFragment.onOptionsItemSelected(NavigationDrawerFragment.java:244)
            at android.support.v4.app.Fragment.performOptionsItemSelected(Fragment.java:1608)
            at android.support.v4.app.FragmentManagerImpl.dispatchOptionsItemSelected(FragmentManager.java:2012)
            at android.support.v4.app.FragmentActivity.onMenuItemSelected(FragmentActivity.java:378)
            at android.support.v7.app.ActionBarActivity.superOnMenuItemSelected(ActionBarActivity.java:244)
            at android.support.v7.app.ActionBarActivityDelegateICS.onMenuItemSelected(ActionBarActivityDelegateICS.java:164)
            at android.support.v7.app.ActionBarActivity.onMenuItemSelected(ActionBarActivity.java:130)
            at android.support.v7.app.ActionBarActivityDelegateICS$WindowCallbackWrapper.onMenuItemSelected(ActionBarActivityDelegateICS.java:308)
            at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:1101)
            at com.android.internal.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:735)
            at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:149)
            at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:874)
            at com.android.internal.view.menu.ActionMenuView.invokeItem(ActionMenuView.java:490)
            at com.android.internal.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:108)
            at android.view.View.performClick(View.java:3540)
            at android.view.View$PerformClick.run(View.java:14167)
            at android.os.Handler.handleCallback(Handler.java:605)
            at android.os.Handler.dispatchMessage(Handler.java:92)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4558)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
            at dalvik.system.NativeStart.main(Native Method)