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.
Make runCharmHook windows compatible

On windows, hooks (live every other executable) needs an extension. This branch adds support for running powershell and batch scripts as hooks. For powershell, we need to pass in exta arguments to exec.Command()
Add no-op worker
Reverted cmd/jujud/unit.go
Added named pipes support

This branch replaces unix sockets with named pipes on windows.
Add identity provider interface and agent id provider implementation
Valid login test for agent identity provider.
Merge pull request #1 from tasdomas/idprov

Valid login test for agent identity provider.
Add failing tests
Style fixes.
Merge Michael's work and fix some tests
Merge branch 'master' into id-prov
Add user identity provider
Fix some collection names
Copy sessions in pinger
Refactor again...
Update dependencies.tsv
Added MakeMachine mathod to factory.
Factory methods for charms and services.
Add unit methods to factory.