Add runit export format.

Fix #28

data/export/runit/log_run.erb

@@ -0,0 +1,7 @@
+#!/bin/sh
+set -e
+
+LOG=<%= log_root %>/<%= process.name %>-<%= num %>
+
+test -d "$LOG" || mkdir -p m2750 "$LOG" && chown <%= user %> "$LOG"
+exec chpst -u <%= user %> svlogd "$LOG"

data/export/runit/run.erb

@@ -0,0 +1,3 @@
+#!/bin/sh
+cd <%= engine.directory %>
+exec chpst -u <%= user %> -e <%= process_env_directory %> <%= process.command %>