Some minor fixes and improvements.
- [Improvement] A lot of code refactored and improved.
- [Improvement] Nginx reloading is better handled, just when needed.
- [Improvement] Now we don't remove any packages after uninstall App.
- [Improvement] Better exit codes.
- [Improvement] Better stats for API.
- [Improvement] Verify process improved.
- [Improvement] System sites now can not be removed.
- [Improvement] New message for people creating sites with WWW subdomain.
- [Fixed] Log Error-Only not working because Nginx was not restarted.
- [Fixed] Error in some (rare) cases when creating a site an MySQL not installed.