Add a JSON format for existing metrics like this.
```
{
"tags":
{
"metric":"thread_pool",
"name":"thrift-server-pool",
"type":"active_thread_num"
},
"unit":"number",
"value":3
}
```
I add a new JsonMetricVisitor to handle the transformation.
It's not to modify existing PrometheusMetricVisitor and SimpleCoreMetricVisitor.
Also I add
1. A unit item to indicate the metric better
2. Cloning tablet statistics divided by database.
3. Use white space to replace newline in audit.log
Add new features:
1. plugins of Ambari and k8s deploy
2. specified config 'priority_network' to solve some ip problems
Fix bugs:
fix bugs that rebalance does not work in some case.
fix count(*) from union stmt bug
fix some union stmt bugs
fix bugs when try to schema change a clone replica
