Fix return="PREVIOUS_URL" not working when PREVIOUS_URL was the home page

commit 6ea4b865b18aafdf26737e98f43a47a3da5e7820
Merge: 525a32f d717cb3
Author: Adrian Macneil <adrian@adrianmacneil.com>
Date:   Sun Feb 17 11:23:11 2013 +0700

    Merge branch 'refs/heads/master' into develop

commit 525a32f11f5ac7d445d19218764b557228a541bb
Author: Adrian Macneil <adrian@adrianmacneil.com>
Date:   Sun Feb 17 11:21:16 2013 +0700

    Fixed PREVIOUS_URL constant not redirecting correctly when previous URL is the homepage

commit c6aa6f4b91b87435b67b19c905baf9f64051956a
Author: Adrian Macneil <adrian@adrianmacneil.com>
Date:   Sat Feb 16 21:04:14 2013 +0700

    Remove deprecated logout tag