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
Do not clone db sessions in state watcher
Merge pull request #396 from wallyworld/no-session-copy-in-watcher

Do not clone db sessions in state watcher

Fixes https://bugs.launchpad.net/juju-core/+bug/1348032

Do not copy sessions when doing watcher queries.
Merge pull request #287 from gabriel-samfira/windows-jujud-machine

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.

This pull request depends on https://github.com/juju/juju/pull/244
Added named pipes support

This branch replaces unix sockets with named pipes on windows.