Fix stability of front server and child command connections.
Add `pione config` subcommand.
Merge remote-tracking branch 'origin/more-stable-front' into pione-config
Make ignore spawn errors when the command is terminating.
Merge branch 'more-stable-front' into pione-config
Change option name from `--my-ip-address` to `--communication-address`.
Remove an unnecessary line.
Merge remote-tracking branch 'origin/pione-config' into fix-test-problems

Conflicts:
	lib/pione/test-helper/command-helper.rb
	test/command/spec_pione-client.rb