[IOTDB-1761] Add metric framework for IoTDB

[SpriCoder]

We add metric framework for IoTDB, related jira is https://issues.apache.org/jira/projects/IOTDB/issues/IOTDB-1761?filter=allissues and related PR #2748

Details:

1. Doc(zh): https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=184616789
2. Doc(en): https://cwiki.apache.org/confluence/display/IOTDB/Monitor+Module

How to use:

1. Install prometheus, pushgateway and grafana
2. Get into metrics/dropwizard-metrics/src/test/PrometheusRunTest and modify System.setProperty("IOTDB_CONF", "The directory of resources");, IOTDB_CONF here is absolute path of the directory of iotdb-metric.yml.
3. Then start prometheus, pushgateway and grafana(Notice: you need to config prometheus to use pushgateway)
4. Then you run the metrics/dropwizard-metrics/src/test/PrometheusRunTest
5. Visit http://localhost:9091/#(pushgateway), and you can see job = "Dropwizard" here.
6. Visit http://localhost:3000(grafana), add prometheus as datasource, and in panel you can find metrictest:counter{}, In this test you can see this metric plus one at one second.

[SteveYurongSu]

LGTM