[JAV-508] & [SCB-11] Metrics Auto Publish

[zhengyangyong]

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JAV-508 & SCB-11 Metrics Auto Publish

If user include metrics in dependency,the metrics service would auto publish with Java Chassis Producer,also use same transport and endpoint config.
For example if user config rest address 0.0.0.0:8080 in microservice.yaml,then the metrics service will available at http://:8080/metrics

[WillemJiang]

It‘s not a good way to just return the string here.

[zhengyangyong]

I had post a mail discuss it : https://lists.apache.org/thread.html/8c34a561c0c4e34b757e32e58c5a99e205c157326292d479526da4c3@%3Cdev.servicecomb.apache.org%3E

[coveralls]

Changes Unknown when pulling a3f28f7 on zhengyangyong:JAV-508&SCB-11 into ** on apache:master**.

[zhengyangyong]

this will be improve after this PR : #451 had fully discuss via mail