[Issue #62]: ImageServer distribution paths collide

Fixes issue #62

When building ImageServer.proj all files are put into the distribution folder reserved for the Web GUI:

\Distribution\Build\ImageServer_Community\x64\Release\Web

since 

$(DistributionDir)

and 

$(DeploymentOutputPath)

point to this same path.

The proposed changes affect the PostBuild event of
- ClearCanvas.ImageServer.Executable.csproj
- ClearCanvas.ImageServer.ShredHostService.csproj
which now put their files into

\Distribution\Build\ImageServer_Community\x64\Release

and as before, the Web GUI coming from WebApplicationDeployment.wdproj ends up in

\Distribution\Build\ImageServer_Community\x64\Release\web

I hope I am on the wright path and could contribute a little!
Thank you!