[fix] template rendering

Without this fix the result looks like so (grunt-cli v1.2.0):

function (obj) {
obj || (obj = {});
var __t, __p = '';
with (obj) {
__p += '<link rel="stylesheet" type="text/css" href="' +
((__t = ( pathPrefix )) == null ? '' : __t) +
'' +
((__t = ( filename )) == null ? '' : __t) +
'' +
((__t = ( pathSuffix )) == null ? '' : __t) +
'"></link>';

}
return __p
}