Drive-by: log when jujud terminates due to specific login errors
apiserver: changed login failure handling during upgrades and restores

Login attempts may fail during upgrades or restores due to data
manipulations performed (or not performed yet) by these
operations. Instead of reporting a "bad credentials" error in this
case, which is confusing to users and causes unit agents to terminate,
return "maintenance in progress" instead.

Fixes LP #1372752.
Merge pull request #853 from mjs/1372752-api-login-fails-during-upgrade

apiserver: changed login failure handling during upgrades

Login attempts may fail during upgrades due to schema migrations not having been applied yet. Instead of reporting a "bad credentials" error in this case, which is confusing to users and causes unit agents to terminate, return "upgrade in progress" instead.

Fixes LP #1372752.

http://reviews.vapour.ws/r/119/diff/
action-set: a jujuc command for Actions to send values back to state

action-set permits action hooks to define an arbitrary map of params
which will be returned to the state server at the end of the Action.
action-set multiple invocation tests and panics fixed
action-set: a jujuc command for Actions to send values back to state

Addressed fwereade's concerns for PR 415.
action-set: a jujuc command for Actions to send values back to state

This commit moves the Action results update method into the Context
implementation, so that client code is not changing the results map
on its own.
action-set PR tweaks

Addressed:
 - need to keep Action results map segregated from jujuc
 - testing Context interface mock to support this change
 - removed old Context methods
 - changed actionResults inner "error" type to string rather than error
Now tests action results interleave in context
action-set uniter test added

action-set now has a test in worker/uniter/uniter.  This test
demonstrates how action-set overwrites existing values in the
results map.
ActionFinish refactor fix commit

This commit revises action-set behavior to interact correctly with new
ActionFinish logic on worker uniter.
Add the backups list method.
Add the backups API endpoints for list.
Add the API client methods for list.
Add the backups list subcommand.
Fix gocheck imports.
Adjust to baseSuite.
Return an error for a failed type assertion.
Add a missing doc comment.
Fix a typo.