Login pageflow change - eliminate the Login Required page - go straight to the login instead

This is kinda related to JRA-1389.

If you have public browsing turned off, when a user clicks on a project or issue URL (in an email, on a maven site, etc), they end up at an error page. It would be much better if the user instead ended up at the login page (perhaps with an error message) rather than an error page like this.

"ERROR
You cannot view this URL as a guest. You must login or signup for an account.
If you feel this message is wrong, please consult your administrators about getting the necessary permissions."

In fact, reaching this page is not really an error - its part of the normal usage of Jira.

What we find is that peoples' initial reaction is "oops, whats wrong".
For those that know what is going on, its just an extra unnecessary click in the way of their login page.

-Nick