Implementations of chrome.system.cpu|display for ios

- Add auto tests for chrome.system.cpu plugin
- Initial stub implementation of chrome.system.cpu.getInfo for ios
- Add auto tests for chrome.system.display plugin
- Implementation of chrome.system.display.getInfo for ios
Unlikely that you'd need to run this on a background thread, it'll probably run quite quickly.
If you *do* want a background thread, use [self.commandDelegate runInBackground:^{ ... }];