[FLINK-1110] Framework for collection-based execution
[FLINK-1110] Fix MapOperator execution and added simple test
[FLINK-1110] Implement collection-based Cross
[FLINK-1110] Implement broadcast variables for collection-based execution
[FLINK-1110] Add execution on collections for flatMap
[FLINK-1110] Add Collection-Based execution for Reduce Operators

Also fix some bugs resulting from moving stuff between packages
[FLINK-1110] Implement collection-based execution for mapPartition.

Make groupReduce code compliant with pre-java-8 versions, fix java8 tests with moved type information classes.

Fix Various warnings.
[FLINK-1110] Implement collection-based execution for bulk iterations
[FLINK-1110] Started implementing the JoinOperatorBase.

Implemented JoinOperatorBase and test cases.
[FLINK-1110] Add createCollectionEnvironment for Scala
[FLINK-1110] Implement collection-based execution for coGroup
[FLINK-1110] Adjusted test base to run programs both with local executor and collection executor
[FLINK-1110] Implement Collection-Based Execution for Delta Iterations
[FLINK-1110] By default, collection-based execution behaves mutable-object safe.
[FLINK-1110] Adjust tests and fix various issues in the collection-based execution.
[FLINK-1110] Fix IndexOutOfBoundsException in ListKeyGroupedIterator

Occured when calling nextKey() and iterator not consumed with *last* key group.
[FLINK-1110] Fix Reduce and GroupReduce Test Failures
[FLINK-1110] Fix mutable object safe mode for data sources in collection-based execution
[FLINK-1110] Add iteration aggregators to collection based execution
[FLINK-1110] Fix HadoopInputFormat to work without prior serialization.