* Add a new "log_folder" option to the log_plays callback plugin.
A a new option for the log_plays callback plugin which allows the user to
control where the callback where creates log files.
The option can be set via the ANSIBLE_LOG_FOLDER environment variable or in the
Ansible configuration file, e.g.:
[callback_log_plays]
log_folder = /path/to/my/log/folder
