Update powertools to not deploy VS assemblies with the package.

Hi,

over the weekend I noticed that the VSIX installer for the powertools installs a few VS assemblies that should be loaded from the GAC.  This PR fixes the problem by telling the build not to copy these assemblies that are referenced to the output directory.

•	Microsoft.VisualStudio.ComponentModelHost.dll
•	Microsoft.VisualStudio.CoreUtility.dll
•	Microsoft.VisualStudio.GraphModel.dll
•	Microsoft.VisualStudio.ProjectAggregator.dll
•	Microsoft.VisualStudio.Shell.Immutable.11.0.dll
•	Microsoft.VisualStudio.Text.Data.dll
•	Microsoft.VisualStudio.Text.Logic.dll
•	Microsoft.VisualStudio.Text.UI.dll
•	Microsoft.VisualStudio.VSHelp.dll

Tested the package on VS 2012 and VS 2013.  It seems to work fine, ran the tests they passed

Let me know what you think.


Kevin Ransom