Patch to fix variable name in notify var, and to provide option for multiplied delay

Hi!

Nice module, I hope this becomes part of core one day. I've implemented it on my site and it works as advertised, although, I'm only using the delay. I made two small changes, one is a bug and one is a new feature:

1. Notify on/off var was named wrong.

see this:

// Should the user be advised about the remaining login attempts?
-   $notice_user = variable_get('login_security_notice_available_attempts', LOGIN_SECURITY_NOTICE_AVAILABLE_ATTEMPTS);
+
+   $notice_user = variable_get('login_security_notice_attempts_available', LOGIN_SECURITY_NOTICE_ATTEMPTS_AVAILABLE);

2. In our case, we didn't want to increase the delay with each attempt, so I made that a separate option.

Thanks! jacob

P.S. Partially funded by CivicActions and Amnesty International