Rename univ-ab.txt to uab.txt

Hi,

The email format for Universidade Aberta is <student number>@estudante.uab.pt for the students and <teacher / staff name>@uab.pt for the teachers and staff and not @univ-ab.pt
You can see some contact emails of Universidade Aberta in the official page, like this teacher email http://www2.uab.pt/guiainformativo/detailuc.php?uc=995 , and this contact email http://www.uab.pt/web/guest/organizacao/servicos/gcri/contactos .

Thanks for your attention,

Best Regards,
Merge pull request #525 from fdomingos/patch-2

Rename univ-ab.txt to uab.txt