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.