Comprehensive functional test suite

[camuel]

1. Stress tests of Swift including ZeroVM to check upper limits and failure scenarios. Sorting can be used as workload.

scenarios to be added to this issues...

[pkit]

We need the following functional tests:

1. Single nexe execution
2. Single nexe on multiple nodes execution
3. Multiple nexe on multiple nodes execution
4. Distributed execution: multiple nodes, multiple nexe, network services