@WIP: Use local storage to save node form data.

#5961 

WIP

This PR adds JS that uses local storage to save the node form state so that when a user hits "Delete this <content-type>" and then "Cancel", the edited values are still in the form. Example:

Edit a person and changing the "Prefix" field:
![selection_383](https://cloud.githubusercontent.com/assets/4497748/3636776/3eff8d2c-0fe0-11e4-827c-0392a32efad0.png)

The value is held in session storage until the user hits "Save", "Cancel" or dismissing the form with the "X" link. It is also cleared when the user hit "Delete" on the node_delete_confirm.

I mark this as a WIP as this still does not take care of the taxonomy (more complicated because of the JS of the select2).

`os_form_values` => Can be camel case.