Updated register.php/.tpl

Added all the smarty assign and formatted register form into a table
(might reconsider layout)
Created about.php/tpl

Made an about page for CorreoDigi (with temporary information from
technical doc)
Updated login.tpl

Formatted the login form into a table
Changes to header/navbar

Made it so the header adds the header “CorreoDigi” (might need to
change if it’s not needed for all pages). Added new pages to navigation
bar