Support links to be made customizable

[prioux]

Right now the admin can configure a email address for support, and a URL for a support site. Both are optional. The email address show up with the label Email Support while the url shows up as Help Site .

It would be nice if the admin could provide their own label. For instance on our CBRAIN service I modified the layout code so that the Help Site shows up simply as the word Support.

Maybe a way to do this is to decode the configuration value; the admin could enter Support|https://my.site.support.example.com/ for the support site and Mail me!|[email protected] for the email support, and the things before the vertical bars would be used as labels.

[prioux]

Make sure the form where these values are entered document this feature!

[crocodoyle]

Waiting for the user_registration pull request ( #434 ) to be approved before starting this, as the email support configuration is added for the first time there.