Adding a Twitter InputDStream with an example
Minor changes after review and general cleanup.

- Added filters to Twitter example
- Removed un-used import
- Some code clean-up
Merge pull request #8 from radlab/twitter-example

Adding a Twitter InputDStream with an example
Several code-quality improvements to DataHandler.

- Changed to more accurate name: BufferingBlockCreator
- Docstring now correctly reflects the abstraction
  offered by the class
- Made internal methods private
- Fixed indentation problems
Merge branch 'dev-merge' into datahandler-fix

Conflicts:
	streaming/src/main/scala/spark/streaming/dstream/DataHandler.scala
BufferingBlockCreator -> NetworkReceiver.BlockGenerator
Merge pull request #10 from radlab/datahandler-fix

Several code-quality improvements to DataHandler.
Merge branch 'dev-merge' of github.com:radlab/spark into dev-merge
Merge branch 'dev' into dev-merge
Merge branch 'streaming-merge' into dev-merge
Moved Twitter example to the where the other examples are.
Making the Twitter example distributed.

This adds a distributed (receiver-based) implementation of the
Twitter dstream. It also changes the example to perform a
distributed sort rather than collecting the dataset at one node.
Split Time to Time (absolute instant of time) and Duration (duration of time).
Changed variable name form ***Time to ***Duration to keep things consistent.