Create Dialog becomes unusable when chrome local storage quota is exceeded

1. Open the create dialog
2. choose anything except 'blank page'
3. every one of these actions attempts to use 'setItem()', and put something in local storage.
4. If the local storage quote is exceeded, a JS error occurs, and the dialog just sits there, spinning. The user can now no longer create anything except blank pages.

We should handle this error properly, rather than make confluence unusable.