Added Upgradable Switches - #331

Switches can now be upgraded by inserting a CPU or Ram. These have the following effects:

Ram: Message Queue size gets increased by 5 per tier (T1 => 25, T1.5 => 30 etc) effectively allowing up to 50 messages instead of 20  
CPU: Message delay gets reduced by one tick per tier allowing to reduce from 5 to 2.

Do not close the issue please (or reopen if autoclosed) since i am still going to improve the GUI
Maybe a `Driver.driverFor(stack) match { case processor: ... case memory: ... }` would be more stable and readable here?