Allow default-null columns

[Jach]

Issue discussed here: http://www.luciddb.org/forums/discussion/554/couchdb-connector-seems-to-needs-a-consistent-schema-across-json-documentss

It seems that this could be done simply by changing if (params.size() - dupes != paramNames.length) in CouchUdx.java to be a strict >. Thus the couchUDX can return less columns but not more, and the columns not returned will be nulled.