Removed slf4j-simple dependency from streaming component.
Fix Bug in ScalaAggregate Operator and add ITCase
Change Partition Operator to actual general-purpose Operator

It is no longer a special-case operator that can only be used in front
of map-style operations.
[FLINK-1123] Add first-n to Scala API
[FLINK-1120] Add Explicit Partition/Rebalance Operator for Scala API
Update doc with Scala First-N and Partition/Rebalance
Added TPCH query examples for Scala API
Improved Java TPCH query examples
Removed RelationalQuery Java API example