Bug fix for 'reservoir' '$' query notation.

Can someone take a look over this fix to the '$' queries of the reservoir data attachment? I thought I had tested that notation but it turns out I wrote a unit test that doesn't go through the entire parsing pipeline. I failed to notice that the '=' character is a reserved character in the '$' query notation. It is used to constrain the result of the query, ie. '<', '=', or '>' can be used. I've fixed the '$' notation in the reservoir data attachment to use '||' instead of '='. Any suggestions on an alternative notation other than '||' is solicited. We can't use '~' as that is another kind of separator and I want to be relatively consistent between the '%' and '$' notation of this data attachment. Plus we use '~' in other places to mean things that are not equality.