A little cleanup, updated options & dependencies

Changed onValidate option to be called validate_form, and added check for validation function before triggering
Added trigger to clearSessionStorage on form submit if clear_on_submit option is set to true
Limited selectors to elements with name attributes for optimization because name attributes are used as keys for input value storage and retrieval
Processed with JSFormat and JSLint
Added session_storage_prefix to sort of allow namespaces for different forms