use gauge for  metrics reported by containers and one small bugfix
use gauge for clusterwide metrics
Merge branch 'release/2.6.0' of github.com:caskdata/cdap into feature/fix_resourcereport_metrics

Conflicts:
	cdap-app-fabric/src/main/java/co/cask/cdap/internal/app/runtime/distributed/DistributedProgramRuntimeService.java
CDAP-693 handle case where webapp address is not explicitly given
in HA mode for the resource manager.
CDAP-983 move set out of if.
Merge pull request #807 from caskdata/hotfix/CDAP-983-resource-metrics-fix-again

CDAP-693 handle case where webapp address is not explicitly given
Upgrade to netty-http 0.8.0
Unify way to make sure directory exists.
Added AbstractBodyConsumer to simplify implementation of BodyConsumer.
Use BodyConsumer for Dataset addModule REST API.
Make sure test write to tmp directory inside target directory.
Use Location.append instead of “/“ concatenation.
Address review comment.
Make addModule call responds only after the whole request body is received to make sure client can get the 409 conflict status if there is conflict.
Merge pull request #802 from caskdata/feature/fix_resourcereport_metrics

Feature/fix resourcereport metrics
Merge pull request #794 from caskdata/hotfix/large-dataset-jar

(CDAP-874) Hotfix/large dataset jar
CDAP-943 Copy Twill's latest unreleased ApplicationBundler