Solr output connector option to commit at end of job, by default

By default, Solr will eventually commit documents that have been submitted to the Solr Cell interface, but the time lag can confuse and annoy people. Although commit strategy is a difficult issue in general, an option in LCF to automatically commit at the end of a job, by default, would eliminate a lot of potential confusion and generally be close to what the user needs.

The desired feature is that there be an option to commit for each job that uses the Solr output connector. This option would default to "on" (or a different setting based on some global configuration setting), but the user may turn it off if commit is only desired upon completion of some jobs.