DHALSIM Prototype with new synchronization mechanism

This version of DHALSIM provides a new synchronization mechanism for the co-simulation environment between the physical simulators and MiniCPS network. Results should now be repeatable across multiple runs.

In addition, some basic network events are now supported: network delays and network packet loss. These events use the same configuration structure as network attacks and also follow a similar syntax. In the back end, the events are implemented using Linux tc tool