add clusterwide compaction for dbs
add clusterwide compaction for dbs

PRs:
https://github.com/apache/couchdb-chttpd/pull/62
https://github.com/apache/couchdb-fabric/pull/27

COUCHDB-2492

PR: #62
PR-URL: https://github.com/apache/couchdb-chttpd/pull/62
Reviewed-By: Robert Newson <6be1d2eb1da4ad201ef1d6e1cff61f9bfb8675fe@apache.org>

fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb