Debug-log accepts names and/or tags for machines/units. Bug 1320543.
Fix data race

LP # 1386968 may be unrelated to a data race, but this needed to be fixed anyway.
Responding to review feedback.
Merge branch 'master' of https://github.com/juju/juju into 207-fix-data-race-lp-1386968

Conflicts:
	dependencies.tsv
Merge pull request #1031 from davecheney/207-fix-data-race-lp-1386968

Fix data race

LP # 1386968 may be unrelated to a data race, but this needed to be fixed anyway.

* updates `charm.v4` to pick up the api change to the `testing` sub package
* roll that change through the clients of `charm.v4/testing`
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.