cmd/jujud: use appropriate timeout for run tests

Use LongWait for assertions of events that are
expected to occur, as described in testing/constants.go.

Fixes https://bugs.launchpad.net/juju-core/+bug/1362990
cmd/juju: mock out API for RemoveUserCommand tests
mongo: move MongoInfo type
Merge pull request #639 from axw/cmd-juju-removeuser-mock

cmd/juju: mock out API for RemoveUserCommand tests
Merge pull request #637 from axw/lp1362990-cmd-jujud-runtests-timeout

cmd/jujud: use appropriate timeout for run tests

Use LongWait for assertions of events that are
expected to occur, as described in testing/constants.go.

Fixes https://bugs.launchpad.net/juju-core/+bug/1362990
Merge pull request #647 from davecheney/189-mongo-move-mongoinfo-type

mongo: move MongoInfo type

This PR moves the `MongoInfo` type from the `environmentserver/authentication` package to the `mongo` package.

This change is necessary to unblock a larger change which was hitting a circular dependency.

With that said, as this change consists of _removing_ the import of the `environmentserver/authentication` from most packages (and renaming the type), it seems clear in hindsight that the `MongoInfo` type belongs in the `mongo` package.
Remove environs/tools.FindInstanceTools
Address review comments