Implementations of chrome.system.cpu, .display, .memory, .network for ios

Closes #346 (pull request)
- Add auto tests for chrome.system.cpu plugin
- Implementation of chrome.system.cpu.getInfo for ios
- Add auto tests for chrome.system.display plugin
- Implementation of chrome.system.display.getInfo for ios
- Add auto tests for chrome.system.memory plugin
- Implementation of chrome.system.memory.getInfo for ios
- Add auto tests for chrome.system.network plugin
- Implementation of chrome.system.network.getNetworkInterfaces for ios
- Change chrome.socket to reuse/depend on implementation in chrome.system.network