Support cache in emulator

- Fixed bug with AddAzureCacheWorkerRole that instance count was 0
- Fixed bug with download.ps1 scripts related to Start-Process -Wait
- Improved Save-AzureServiceProjectPackage to have local option
- Removed unnecessary line from setup_WebRole/bin/setup_web.cmd
- Changed the WorkerRole/startup.cmd to not be wait while spinning
- Adjusted caching stuff to work with emulator

#592