Updated concurrency example + new ThreadExample

Concurrency example has been renamed into serviceExample (as that is what it is) and a new example project called threadExample has been added.

This new example showcase the use of Threads and ASyncTasks better than the old Concurrency-example.
We should update the new serviceExample to be more simple as it is currently quite complicated, but that is left for another PR.

@emanuelez @kneth @bmunkholm 
Why the anonymous Runnable? We could simple implement the run() method of Thread. One less indentation level :)