Update install/install.sql

Fix font
Update site/views/guestbook/tmpl/default_item.php

update language
Update site/language/en-GB/en-GB.com_tz_guestbook.ini

Update language
Update site/views/guestbook/tmpl/default_item.php
Update tz_guestbook.xml

update email
Merge pull request #2 from Tunguyen12689/master

Update version 1.1.3