STORM-302: Fixes Indentation for storm-dist pom.xml files
Add Null Check before registering a metric.
Addressed review comments
Merge branch 'metrics-register' of https://github.com/revans2/incubator-storm

STORM-235: Registering a null metric should blow up early
Updated CHANGELOG.md for STORM-235
Merge branch 'change-pom' of https://github.com/srinivasgumdelli/incubator-storm

STORM-302: Fix Indentation for pom.xml in storm-dist
Added Changelog for
STORM-302: Fix Indentation for pom.xml in storm-dist