Marvin testing

@MartinSenne 

as discussed, a proposal containing
1) RemoteFuture factory 
2) Inheritance to Runnable
3) createRunnable method within RemoteFuture impl.

Warning, code does not compile due to certain questions such as

a) why do we need to pass a promise as parameter to PromiseCompletingRunnable ? 
// class: org.remotefutures.core.impl.RemoteFuture

b) apply signature needs to be aligned to RemoteExecutionContext. 
Would you please look at it? 

Once these things are fixed, things should work as expected