support for device compatibility checks

[schrnz]

Idea: only use devices that pass a per evaluation compatibility test as different evaluations have different requirements. Example requirements:

• specific Android version(s)
• packages installed or not
• rooted or not

The straightforward way to implement this is to add a corresponding method to the IEvaluator interface and check all devices before spawning their helper processes. However, chances are high that we will see simple checks like the ones mentioned above over and over, so it might be beneficial to provide implementations for them, maybe in a utility class.