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

* new jobs module for m/r related code
* accumulo source/tap for scalding
So normally this would be done in the pom with a shaded jar that contains all the dependencies you need. At first I didn't include this filtering, but then it copied the entire classpath for geoserver/accumulo along with the job, and it took a long time to run.
We do have the geomesa-jobs pom inside the jar, so we could access that... but I don't think we could maven-resolve to get the transitive dependencies (without requiring maven and maven repos to be available at runtime).
Maybe as part of the maven build we could create a text file with the transitive jars, then read that in here? That might be possible.