Add booth-cfg-name attribute to ticket

[jfriesse]

This is mostly to be able to mark what tickets were created by booth and what specific booth instance it was. The idea is mostly to allow pcs remove booth tickets, which were removed from config. It is questionable if booth itself should cleanup old (in config file non-existing) tickets or not, but if so, this can be different issue/PR/commit.

booth-cfg-name should be same as used in pid file so booth_conf->name

More context can be found in https://issues.redhat.com/browse/RHEL-7602