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

• Fixes for building COPR Backend and Dist-git on EL7
• simplified/improved logging of exceptions mainly
• don't use sha256 checksum for rhel-5* repos, too
• drop mentions of the max_builds_per_vm optoin
• switched usage of deprecated ansible Runner for python-paramiko module
• os_nova filter plugin fixed for python-novaclient 3
• support for STOMP msg buses
• fix Bug 1402689 regarding job cancellation
• jobgrab service is no more
• respect 'do_sign' option when forking
• fix buildroot_cmd for rhel mock profiles