Cleanup.
Merge branch 'hds' of https://github.com/DataTorrent/Malhar into hds
Merge pull request #1075 from tweise/hds

Cleanup.
Create separate package, fix warning and other basic issues.
Merge pull request #1079 from tweise/hds

Create separate package, fix warning and other basic issues.
Adding JSON AdInfo generator and JSON converter operators; Integrating new operators into generic app
Merge pull request #1080 from sashadt/hds

Adding JSON AdInfo generator and JSON converter operators; Integrating n...
Fix DAG validation.
Fix typecasting during calculating aggregate values for numbers.
Change key and metrics names
Generate aggregators from event description.
Adding subclass of DimensionsComputation which generates aggregators
internally based on event schema.