Update the user manager commands.
Don't kill instances if there are errors talking to mongo
Fix some error typos
Merge pull request #282 from wallyworld/provisioner-destroys-instances-incorrectly

Don't kill instances if there are errors talking to mongo

The provisioner was killing all deployed instances if it could not talk to the mongo database. 
This fixes that.
Update doc comments.
Merge pull request #277 from howbazaar/env-cmd-user-mgr

Remove EnvName from user manager juju commands

In further work to hide the environ command EnvName, the branch updates the various user manager commands.
state/apiserver: apiInfo.EnvironTag is now a Tag
test fixups
Merge pull request #284 from davecheney/133-names-refactor-part-vi

ApiInfo.EnvironTag now takes a names.Tag
Merge branch 'master' of https://github.com/juju/juju into peergrouper-ipv6-testing
Some simplification after review.