Sometimes because of errors that may need to check the status of the currently installed feature.
Also possible when uninstall feature, there did not delete the files.
Additional write two functions can do these actions
1. Check feature status
2. Feature status
Missing - file not exists
MD5 - MD5 not match in zip and filesystem
Success - Success
3. Clear feature files
ASP.NET Deployment Solution - Part 1
ASP.NET Deployment Solution - Part 2