add support for minimum distance on near-query

[kcoleman-marklogic]

I might just be overlooking this, in which case I apologize for the noise, but it does not look to me like StructuredQueryBuilder.near supports the "minimum-distance" option added to near query for ML9. I didn't see it mentioned in the Java API deltas spec, either.

This feature manifests in structured query as a new minimum-distance element of near-query.

[sammefford]

@georgeajit I only added a test of the XML structure. Could you add a test that runs a near-query against the server with minimumDistance and make sure it's working end-to-end?