Fast forward internal repl. between file copies

In the case where two files have the same UUID we can analyze epoch
information to determine the safe start sequence.

BugzID: 27753
Merge pull request #67 from cloudant/27753-fast-forward-shard-copies

Fast forward internal repl. between file copies

BugzID: 27753
Allow mem3_shards:local to take a list or binary

BugzId: 29571
Get the shard suffix for a given database

This grabs the shards for the given database name, and then pulls out
the first shard and extracts out the suffix. mem3:shards is ets
backed, so in the general case this should be fast.

BugzId: 29571
Merge pull request #70 from cloudant/29571-metadatadb

29571 metadatadb
Remove mem3_util:owner
Merge pull request #71 from cloudant/31712-remove-owner-fun

Remove mem3_util:owner
Replace margaret with couch_stats

Also add stats_descriptions.cfg.

BugzID: 16742