Set requestHandler in ExternalFileQueryGenerator / QueryOperation

[GoogleCodeExporter]

We have a use-case where we want to try SolrMeter against custom request 
handler(s).  Right now there doesn't seem to be a way to override the default 
/select request handler. Can the code for SolrMeter be extended to take a 
configuration parameter for the request handler name? This can then be set on 
the SolrQuery object by calling SolrQuery.setRequestHandler().

Original issue reported on code.google.com by dipanjan...@gmail.com on 27 Apr 2015 at 6:10