feat(model/message_handler): Add time to log message output

[jchauncey]

Testing Instructions:

• clone this PR
• make build push upgrade
• checkout the corresponding fluentd PR - https://github.com/deis/fluentd/pull/61
• make build push upgrade in the fluentd directory
• Deploy an application that you can use to generate log entries with.
• Use deis logs to see new message format.

The log format should look similar to this -

2016-10-18T20:24:06+00:00 app[foo.web.v4]: 2016/10/18 20:24:05 10.240.0.7 GET / - 6334824724549167320
2016-10-18T20:24:07+00:00 app[foo.web.v4]: 2016/10/18 20:24:06 10.240.0.7 GET / - 605394647632969758
2016-10-18T20:24:07+00:00 app[foo.web.v4]: 2016/10/18 20:24:07 10.240.0.7 GET / - 1443635317331776148
2016-10-18T20:24:08+00:00 app[foo.web.v4]: 2016/10/18 20:24:07 10.164.2.1 GET / - 894385949183117216
2016-10-18T20:24:08+00:00 app[foo.web.v4]: 2016/10/18 20:24:07 10.240.0.5 GET / - 2775422040480279449
2016-10-18T20:29:03+00:00 deis[controller.INFO]: buildpack type detected. Defaulting to $PORT 5000
2016-10-18T20:29:03+00:00 deis[controller.INFO]: buildpack type detected. Defaulting to $PORT 5000
2016-10-18T20:29:03+00:00 deis[controller.INFO]: scaling Deployment foo-web from 1 to 4 replicas
2016-10-18T20:29:04+00:00 deis[controller.INFO]: adding 30s on to the original 120s timeout to account for the initial delay specified in the liveness / readiness probe
2016-10-18T20:29:04+00:00 deis[controller.INFO]: This deployments overall timeout is 300s - batch timout is 150s and there are 2 batches to deploy with a total of 4 pods
2016-10-18T20:29:14+00:00 deis[controller.INFO]: waited 10s and 4 pods are in service
2016-10-18T20:29:24+00:00 deis[controller.INFO]: waited 20s and 4 pods are in service
2016-10-18T20:29:34+00:00 deis[controller.INFO]: waited 30s and 4 pods are in service
2016-10-18T20:29:38+00:00 deis[controller.INFO]: admin scaled pods web=4

[deis-bot]

@krancour, @arschles and @mboersma are potential reviewers of this pull request based on my analysis of git blame information. Thanks @jchauncey!

[codecov-io]

Current coverage is 41.68% (diff: 100%)

Merging #123 into master will increase coverage by 6.51%

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+ Hits            134        163    +29   
+ Misses          227        208    -19   
  Partials         20         20          

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[kmala]

@jchauncey i think you need to change the existing e2e test along with this