Encapsulate index table

[keith-turner]

It would be nice to create an internal API for the external webindex search table. Fluo and Spark code write to this table. Web app code reads from it. The code for interacting with this external table is spread far and wide. Would be nice to bring that code together into once place and have a simple API for it. This would have made a change like #71 easier to make and more important test. I manually tested the changes for #71. If the webindex search table had its own internal API, then that could have test.