Refactor how webindex obtains Accumulo config

[keith-turner]

Currently webindex does some odd things because it obtains Accumulo config from Fluo config for its external Accumulo index. I think it would be cleaner if Accumulo info were explicit webindex config. Then webindex could use its Accumulo config to configure Fluo and its external index table. With this approach I think all init could be done Java, avoiding editing the app props file and then calling fluo init.