This code fixes the todo items mentioned on the SolrCloud wiki:
-optionally allow user to query by collection
-optionally allow user to query by multiple collections (assume schemas are compatible)
We are going to put a patch to see if anyone has any trouble with this code and/or if there is any comments on how to improve this code.
Unfortunately, as of now, we don't have a test class as we are working on it. We are sorry about this.