Added PSH option to windows/local/ask exploit

Gives you the ability to use powershell to 'ask' for admin rights if the user has them.  Using powershell makes the pop up blue instead of orange and states that the company is Microsoft, it also doesn't drop an exe on the system.  Looks like 32 bit https works but if you migrate out you lose priv and if you run cachedump the session hangs.