Add append project option to nuget publish feed

The purpose of this feature is so that people can push to in house nuget repos and have more control over the organization.  For example artifactory allows you to push to a custom nuget path lets say:
```
http://artifactory/api/nuget/nuget-local/[orgName]/[packageName]/[packageName].[version].nupkg
```

This allows artifactory to create a folder structure for better package management.