Splitting the common package into a common and a common.net package so that common really only has the common properties / targets

#20
Merging the build properties for the C# package.
Adding the WiX package

#20
Updating the nBuildKit settings to match the sample ones

#20
Making sure that all the files generated from the public key extraction processes are removed.
Ensuring that the DirWorkspace is always available

#20
Merge pull request #20 from pvandervelde/issue/wixpackage

MsBuild.Projects: Provide scripts for WiX projects