Undo semantic change of email template placeholders

There are various email template placeholders like SITE_URL and RESET_URL, which used to be used in the templates like this:

<a href=\"SITE_URL\">SITE_URL</a>

but got switched to raw reference like:

SITE_URL

The changes make it so that the class generating the full email content now includes the HTML syntax for the link (e.g. https://bitbucket.org/xnatdev/xdat/commits/3bdf87c1b2b464e40160682b1a1488d99c6b27a7#Lsrc/main/java/org/nrg/xdat/turbine/modules/actions/XDATForgotLogin.javaT106). This works fine for new XNAT installations, but for any previous XNAT installations, they will already have the older templates cached in the database which won't work with the new placeholder values. Instead of changing the meaning of placeholders, it's probably best to define new placeholders if you need to modify the semantics of the placeholder, as otherwise we lose all backwards compatibility.