Deactivate workers for windows

Authenticationworker and rsyslog workers are not supported on windows yet. The authentication worker will be ported on windows to add support for winrm. Rsyslog is not supported on windows yet.
Add no-op worker
Reverted cmd/jujud/unit.go
Added named pipes support

This branch replaces unix sockets with named pipes on windows.
wip
environs/config: introduce config.UUID()

Introduce `config.UUID()` method to access the uuid of the environment.

A uuid is the canonical indentifier for an environment, and superceeds the environment's name.

For backwards compatability, `config.UUID()` is currently permitted to return "", but once all environments are converted to have an environment uuid in place, this method will change to return a valid uuid for a valid config.
Tests pass, removed @local
Logic change, create no longer errors if it exists as the exist check isn't done until write, so we try to read it first.
replicaset: rework the test to not start two mongodb replicas during the IPV6 test
Remove the error from Create as it can't fail now, and remove new file serialization structures.
Provision new instances with version.Current

New instances were being provisioned with the agent-version from the
environ config instead of the currently running tools version. This
meant that there was a risk of new instances not running upgrade steps
if a juju upgrade occurred around the same time as the instance was
provisioned.
Remove the unneeded server uuid for now.
Merge branch 'master' of https://github.com/juju/juju into 150-environs-config-grow-a-uuid-method
Permit uuid to be set if unset, otherwise refuse to set it.
Merge pull request #380 from howbazaar/configstore-no-file-until-write

Configstore no file until write

Change the ConfigStore so newly created EnvironInfo instances do not persist until they are written.

Changes the writing of the files to use a fslock instead of writing to a temporary file and renaming as a prelude to the changes coming where there will be multiple files related to a single environment connection (connection file, server file, and maybe a separate identity file)

CreateInfo now cannot return an error.

The diskinfo implementation now also separates the member storage from the persistence structure.
Merge branch 'master' of https://github.com/juju/juju into 150-environs-config-grow-a-uuid-method
worker/apiaddressupdater: clarify docs
worker/peergrouper: don't call SetAPIHostPorts unless changed

We're spamming the transaction log with SetAPIHostPorts
transactions even when the addresses have not changed.
This change stops that from happening.

Fixes https://bugs.launchpad.net/bugs/1345832
Oops.
Precreate the txns collection at the same time as the txn.logs collection