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.
Store backups data/metadata in a separate mongo database.
Use a DB info struct with information about which databases to dump.
Build the backup dump info from juju state.
Explicitly identify the auth DB.
Factor out the mongodump command to be more versatile.
Dump each database separately.
Dump everything and clean up afterward.
Use the backups database.
Drop a superfluous comment.
Use sets for the DB targets.
Return an error instead of panic.