Adding hybrid custom error handling

Making updates so that hybrid apps can also customize their auth error handling.  The new error handling essentially goes like this:

- First, in the default case, nothing changes—unhandled errors will be displayed via an alert view dialog.
- If the developer removes one or more error handling filters and an error falls through to the `loginWithCompletion:failure` error block, the following occurs:
    - If it's during the page load process, or during the refresh of an expired session, the user will be taken to the error page configured in `bootconfig.json`, or a default page if the error page doesn't exist.
    - If it's during authentication through the OAuth plugin, the error will be returned on the error callback.