Modify the `README.md` to illustrate how to use this cookbook.

This commit refs #88.
Add an attribute for allow `forward` source.

Add an attribute for toggling the `forward` source configuration.
Default value is `false`,
which means: do not receive forwarded logs from remote hosts.

This commit refs #88.
Receiving forwarded logs from remote hosts.

- Add configuration file for receiving logs from remote hosts.
- Deploy the configuration file for receiving the forwarded logs.

This commit refs #88.
Allow remote hosts to connect via 24224 port.

This commit refs #88.
Merge pull request #88 from kazu634/id/88

`td-agent`の部分でテストが失敗しているだけなので、マージします。