State: Migrate instanceId

Add an upgrade step to migrate the depricated "instanceid" machine
field into "instanceid" in the instanceData doc.
fix conflicts
State, upgrade step: Add EnvUUID to Sequence doc IDs

Adds an upgrade step to add the EnvUUID to sequence doc IDs.
State upgrade step: Add EnvUUID to cleanup docs.

Add an upgrade step which stringifies the cleanup doc (bson.ObjectId)
and prepends State's environment UUID. Update state.docID() to take an
interface and return a string.
Changed warning display for unknown config, remove tools-url on upgrade, added/modified tests. Bug 1383070.
generate-tools now merges metadata from different streams
Add a --download option to "juju backups create".
Add a --filename option.
Drop superfluous if statement.
Use a more meaningful (in help) "default" for --filename.
version: Reset version to alpha3

An earlier branch accidentially reverted the version to alpha2,
change it back to alpha3 here.
Upgrade gomaasapi to v 58

Fixes https://bugs.launchpad.net/juju-core/+bug/1384001
Merge pull request #1005 from bz2/re_alpha3_1387764

version: Reset version to alpha3

An earlier branch accidentially reverted the version to alpha2,
change it back to alpha3 here.
Add a recommendation to download backups.
Fix tests.
Merge pull request #1004 from perrito666/fix_1384001

Upgrade gomaasapi to v 58

Fixes https://bugs.launchpad.net/juju-core/+bug/1384001
fix conflicts
Merge branch 'master' of https://github.com/juju/juju into migrate-instanceid
Merge pull request #994 from waigani/migrate-cleanup

State upgrade step: Add EnvUUID to cleanup docs.

Add an upgrade step which stringifies the cleanup doc (bson.ObjectId)
and prepends State's environment UUID. Update state.docID() to take an
interface and return a string.
Merge pull request #1002 from ericsnowcurrently/backups-create-download

Add --download and --filename options to "juju backups create".