Form name setting

I am using the library in a project that needs to auto save the form data and is working well.
The html form that is used does not have a name attribute and does not need one, as a result the key that is used to save the data has "undefined" in it (looks a bit messy)
So I have added another option to the library to say dont put the form id and form name as part of the key but just put a "/" instead.

Hope this is suitable for merging into the master branch.

Thanks