for comments - GEOMESA-233 adding scalding job to index attributes through geoserver UI

Still TODO - 
* create ticket for the TODO in the code
* error handling in UI for failed m/r jobs
* unit tests

close - i was trying to check the first path for all the jars, then check the next path for any that weren't found in the first path, etc.
the idea was to only load the paths as required, in an attempt to save some overhead... e.g. if everything is found in the first path, we never bother with the rest. the code did end up a bit convoluted though... got any suggestions that would only load each jar from the first place found and stop processing paths once everything was found?