run all powershell commands with -ExecutionPolicy Bypass to avoid failures on a fresh OS thats non 2012R2

Ran into this running on win 8.1

Unless a user has already explicitly set the powershell Execution policy on the machine to atleast RemoteSigned, the busser setup will fail on all OSs other than 2012R2 which has a default ExecutionPolicy of RemoteSigned.

This can be avoided by starting powershell.exe with `-ExecutionPolicy Bypass` which bypasses the policy rules.

I have also filed an issue against the dsc cookbook with the same problem.

Both can be worked around if the cookbook has:

```
powershell_script "set execution policy" do
  code <<-EOH
    Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Force
    if(Test-Path "$env:SystemRoot\\SysWOW64") {
      Start-Process "$env:SystemRoot\\SysWOW64\\WindowsPowerShell\\v1.0\\powershell.exe" -verb runas -wait -argumentList "-noprofile -WindowStyle hidden -noninteractive -ExecutionPolicy bypass -Command `"Set-ExecutionPolicy RemoteSigned`""
    }
    EOH
end
```

Which sets the execution policy for both 64 and 32 bit shells. Need the 32 bit shell set since chef-client is 32 bit.