Cleanup ConfirmDialogFragment

Currently, the app name briefly flickers when ConfirmDIalogFragment finishes.

These changes make the flicker less noticeable:
* Set the app name blank in the Manifest
* Dismiss the dialog fragment and finish the activity

Also updated ConfirmDialogFragment to have a flexible message body (second parameter)

* And updated gitignore to ignore artifacts from Android Studio's "Layout Inspector" tool