Merging logstream branch into Malhar master

The logstream application can be found under apps directory. It contains both old and the new versions.

The old version has operators added to the dag for each type and filter. It emits the results to
redis db similar to siteops for siteops UI to consume. 

The new version is optimized to have a single line of logical dag which partitions itself based on log types and filters applied on each type. It also sends meta information to the each aggregation such as type, filter, dimension etc to uniquely identify the aggregation. The results are emitted using the widget output operator to be viewed on the new widgets UI.

For old version, please see apps/src/main/java/com/datatorrent/apps/logstream/Application.java
For new version, please see apps/src/main/java/com/datatorrent/apps/logstream/Application1.java