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

- 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
Honestly, our use of the terms stable/beta/alpha suck anyway.  We should have a table that measures coverage, not quality.  Api is implemented "fully", "mostly", "barely", "none", or something like that.  Thats how other projects do it as well (i.e. http://clang.llvm.org/cxx_status.html)