Bug 3754: Follow-up patch

Bug 3754: Follow-up patch

This patch is a follow-up patch for the one submitted by
Nahuel Angelinetti for Bug 3754 (for 3.0.x).

The bug is mentioned here:

Bug 3754 - Language detection doesn't take really care of syspref
http://bugs.koha.org/cgi-bin/bugzilla3/show_bug.cgi?id=3754

Nahuel's patch is here:
http://git.koha.org/cgi-bin/gitweb.cgi?p=Koha;a=commitdiff;h=df25509e8c500c0e91b9f2343ebca1c7c98238cf

I had a problem which was being uncapable of changing from
"Português" (Portuguese) to "English" and vice-versa. The problem
was solved after applying Nahuel's changes followed by this patch
of mine.

This patch is for 3.0.x (because it follows up on Nahuel's
patch that was also for 3.0x). I'll let one that can test these
two patches (Nahuel's and mine) for the "master" branch to test
them and submit it for that branch.