Upgrade fluentd to 1.3.0, ability to deal with octet counting messages

[lurraca]

In the fluentd 1.3.0 they added support for frame_type -> octet_count

https://www.fluentd.org/blog/fluentd-v1.3.0-has-been-released

We would like to make use of that feature while using stackdriver-tools.

P.S.: fluent-plugin-google-cloud dependecy of fluentd would also need updating.

[mattysweeps]

Per our discovery, we are blocked until the fluent-plugin-google-cloud updates it's dependency on fluentd:
GoogleCloudPlatform/fluent-plugin-google-cloud#282

[scottmuc]

@mattysweeps looks like plugin has been updated to work with a more recent version of fluentd. Is there a way we could bump the priority of this? With the release of PCF 2.7 it might be a good excuse to bump the stemcell dependency too.