Made more informative warnings

lib/SugarTrail/Template/Condition.pm

     if (exists $self->{handlers}->{$op}) {
         return &{ $self->{handlers}->{$op} }($want, $have);
     } else {
-        $self->warn("unknown operator: $op");
+        $self->warn( sprintf (
+            "unknown operator: '%s' in '%s'",
+            $op,
+            $self->{string}
+        ));
     }
 }