Pull Request for added "where" option

I've made these changes in the version of fusiontips that I'm using on my project, but it may be helpful to others as well.  This change allows filtering of the set of results to select from.  In my case I had several fusion table rows with the same location and was using a "where" in the FusionTablesLayer query to display at most one of them at a time.  When mousing-over the dot (without the "where" option in enableMapTips), the incorrect row was returned based on location match.