Start centralizing all init script templates
Rename unicorn_worker_processes to 'workers'
Rename unicorn_pidfile to pidfile
Add header for unicorn defaults template
Rename unicorn_socket to socket
Rename unicorn_backlog to backlog
Simplify unicorn logging controls

If the logdir path param is set, then enable logging and write logs to
that directory. If it's unset, disable logging. Fewer twiddly bits.
Rename unicorn_user and unicorn_group to user and group
Reorder config variables for clarity