Debug-log accepts names and/or tags for machines/units. Bug 1320543.
Add tests for --download and --filename.
--download -> --no-download.
Add a warning for --no-download.
Refactor some nested if statements.
Move some conditional messages to better spots.
Use Time.Format().
Merge pull request #1037 from ericsnowcurrently/backups-download-by-default

Make download the default for "juju backups create".
Added comments. Renamed agent to agentTag. Re-ordered tests. Bug 1320543.
Added comments. Bug 1320543.
Typo. Bug 1320543.
Renamed field to index. Bug 1320543.
Add an issue # to a TODO comment.
Merge pull request #1025 from anastasiamac/Bug1320543-debuglog-names-vs-tags

Debug-log accepts names and/or tags for machines/units. Bug 1320543.
Merge pull request #972 from ericsnowcurrently/backups-limited-dump

Limit backups to dumping certain databases.

This patch takes an opt-out approach, explicitly ignoring the backups and presence databases.  This requires some trickiness with mongodump: --oplog isn't supported with the --database option.  We are going with option 2 on https://lists.ubuntu.com/archives/juju-dev/2014-October/003818.html.  However, we are not using the --oplog option.  That will be addressed in a subsequent patch.
Dump the oplog.
Add oplog-focused tests.
Fix test oplog marshalling.
Strip oplog entries for ignored databases.
Unmarshal oplog.bson all at once (a simpler approach).