job definition filter implementation /issue #9
Package common filters inside logstash package.  Also allow pulling external filters (e.g., https://ci-logsearch.s3.amazonaws.com/logsearch-filters-cf/logstash-filters-cf-7.tgz)
Copy raw/ filters recursively, but flatten into composite/ folder to ensure sorting done by filter file name (rather than filter folder name)
Fix cut 'n paste mistake.  Bad @mrdavidlaing
Merge pull request #20 from logsearch/issue-9

job definition filter implementation /issue #9