JFG-701
+ add attributes to metric-aggregator element in schema
+ change parser little bit
+ add setter for AggregatorsSettingsMap
+ renaming of attributes to matches with analogs in environment.properties
- revert logic with default metrics names
- revert logic with aggregator-ref
- public -> private
+ add unit tests.
+ add few metrics into testNewConfiguration(sleep-service-5ms) with aggregators with settings.
Merge branch 'master' of github.com:griddynamics/jagger into aggregators-settings-in-schema

Conflicts:
	chassis/core/src/main/java/com/griddynamics/jagger/engine/e1/aggregator/workload/MetricLogProcessor.java
	chassis/core/src/main/java/com/griddynamics/jagger/engine/e1/collector/MetricAggregatorSettings.java
	chassis/core/src/main/java/com/griddynamics/jagger/engine/e1/collector/MetricDescription.java
- setter for aggregatorsWithSettings
- docu for MetricAggregatorSettings
Merge pull request #485 from amikryukov/aggregators-settings-in-schema

JFG-701