Template Toolkit for RemoteAuth

Template Toolkit for RemoteAuth

With this commit, RemoteAuth handlers can now use TT2 templates to
manage the format and content of responses.  This will make it easier
for admins to control what patron information is included in a
successful auth response, among other things.

TT2 support is provided by a new OpenILS::WWW::RemoteAuth::Template Perl
module.  (EGWeb has too much overhead and is not well-suited to this use
case.)

Signed-off-by: Jeff Davis <jeff.davis@bc.libraries.coop>