Now `with-backdrop` and `modal` can be added or removed on dialogs!

Two updates being pushed to fix open-close dialog:

• paper-dialog-behavior 1.0.4 -> 1.0.5
• iron-overlay-behavior 1.0.7 -> 1.0.8

And those enables the dialog to apply with-backdrop or modal or without them meantime not suffering from dialog closes itself after any clicking/ tapping.