Benchmark for review

@MartinSenne Please review & merge

Finally, first draft of the benchmark. 
I've created a SBT sub-project that contains the benchmark.

Important documents to start with:
* benchmark/Readme 
=> Contains  quickstart 
* benchmark/org.remotefutures.main/Blueprint 
=> contains details how to write custom task for measurement
* doc/Benchmark. 
=> contains most of the details