Tomcat doesn't starts on boot (Yosemite) or launchctl operation already in progress

After Yosemite, Tomcat installation refused to start on boot. When trying to start it manually, using:

sudo launchctl load /Library/LaunchDaemons/org.apache.tomcat.plist


failed with message:

launchctl operation already in progress


It took me a while to discover that:

• launchctl has changed a lot after Yosemite (and you need to read the only available documentation, man launchctl)
  
• most commands (like load) are in deprecated mode
• all tomcat files where with "@" extended attribute (ls -l@ gives a list with extended attributes) meaning that are signed with "com.apple.quarantine" (you need to approve execution explicitly on the first run)
• the command:
  
launchctl print-disabled system
  
  lists org.apache.tomcat as disabled

Solution:
- Remove the quarantine attribute
xattr -r -d com.apple.quarantine /opt/servers/Tomcat/TomcatHome

- Enable service
sudo launchctl enable org.apache.tomcat

- Add service to the system domain
sudo launchctl bootstrap system /Library/LaunchDaemons/org.apache.tomcat.plist