cancel build fix

• extend check for a builder package present on a builder machine
• arbitrary dist-git branching
• remove --add-cache-id from appstream-builder call, see Bug 1426166
• change to using a standalone builder package

Fixes downloading logs for failed builds.

• do not condrestart optional logstash service
• standalone builder option
• build reattaching after copr-backend(-build) service restart
• live mockchain log
• use openssh instead of paramiko
• update cleanup_vm_nova script
• remove buggy logging
• removed Sphinx as a dependency...
• verbose log everything we have about failed playbook
• replace fedorahosted links
• make systemd services out of ActionDispatcher and BuildDispatcher